Evaluated kinetic and photochemical data for atmospheric chemistry: Volume IV – gas phase reactions of organic halogen species

R. Atkinson; D. L. Baulch; R. A. Cox; J. N. Crowley; R. F. Hampson; R. G. Hynes; M. E. Jenkin; M. J. Rossi; J. Troe; T. J. Wallington

doi:10.5194/acp-8-4141-2008

Atkinson, R.;Baulch, D. L.;Cox, R. A.;Crowley, J. N.;Hampson, R. F.;Hynes, R. G.;Jenkin, M. E.;Rossi, M. J.;Troe, J.;Wallington, T. J.;

2008-08-04 00:00:00

Atmos. Chem. Phys., 8, 4141–4496, 2008 Atmospheric www.atmos-chem-phys.net/8/4141/2008/ Chemistry © Author(s) 2008. This work is distributed under the Creative Commons Attribution 3.0 License. and Physics Evaluated kinetic and photochemical data for atmospheric chemistry: Volume IV – gas phase reactions of organic halogen species 1 2 3 4 5 6 7 8 R. Atkinson , D. L. Baulch , R. A. Cox , J. N. Crowley , R. F. Hampson , R. G. Hynes , M. E. Jenkin , M. J. Rossi , 9 10 J. Troe , and T. J. Wallington Air Pollution Research Center, University of California, Riverside, California 92521, USA School of Chemistry, University of Leeds, Leeds LS2 9JT, UK Centre for Atmospheric Science, Dept. of Chemistry, University of Cambridge, Lensﬁeld Road Cambridge CB2 1EP, UK Max-Planck-Institut fur ¨ Chemie, Division of Atmospheric Chemistry, Postfach 3060, 55020 Mainz, Germany U.S. Dept. of Commerce, National Inst. of Standards and Technology, Bldg. 221, Rm A111, Gaithersburg, MD 20899, USA CSIRO Energy Technology, Lucas Heights Sci. and Technol. Centre, Building 2, PMB7, Bangor, NSW 2234, Australia Dept. of Environmental Science and Technology, Imperial College London, Silwood Park, Ascot, Berkshire SL5 7PY, UK Laboratoire de Pollution Atmospherique ´ et Sol (LPAS/ENAC), Ecole Polytechnique Fed ´ erale ´ de Lausanne (EPFL), Bat ˆ CH H5, Station 6, 1015 Lausanne, Switzerland Institute of Physical Chemistry, University of Gottingen, ¨ Tammannstr. 6, 37077 Gottingen, ¨ Germany Ford Motor Company, Research and Advanced Engineering, Mail Drop RIC-2122, Dearborn, Michigan 48121-2053, USA The IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry Received: 12 June 2007 – Published in Atmos. Chem. Phys. Discuss.: 23 November 2007 Revised: 6 May 2008 – Accepted: 6 May 2008 – Published: 4 August 2008 Abstract. This article, the fourth in the series, presents ki- stituted in 1977 and tasked to produce an evaluation of rel- netic and photochemical data sheets evaluated by the IUPAC evant, available kinetic and photochemical data. The ﬁrst Subcommittee on Gas Kinetic Data Evaluation for Atmo- evaluation by this international committee was published in spheric Chemistry. It covers the gas phase and photochem- J. Phys. Chem. Ref. Data in 1980 (Baulch et al., 1980), fol- ical reactions of organic halogen species, which were last lowed by Supplements in 1982 (Baulch et al., 1982) and 1984 published in 1997, and were updated on the IUPAC website (Baulch et al., 1984). In 1986 the IUPAC Subcommittee in 2006/07. The article consists of a summary sheet, contain- on Data Evaluation superseded the original CODATA Task ing the recommended kinetic parameters for the evaluated Group for Atmospheric Chemistry, and the Subcommittee reactions, and four appendices containing the data sheets, has continued its data evaluation program with Supplements which provide information upon which the recommendations published in 1989 (Atkinson et al., 1989), 1992 (Atkinson are made. et al., 1992), 1997 (Atkinson et al., 1997a), 1997 (Atkin- son et al., 1997b), 1999 (Atkinson et al., 1999) and 2000 (Atkinson et al., 2000). Following the last of these reports, Supplement VIII (Atkinson et al., 2000), the evaluation has 1 Introduction continued to be updated and published on the worldwide web (http://www.iupac-kinetic.ch.cam.ac.uk/). The IUPAC web- In the mid 1970s it was appreciated that there was a need site hosts an interactive database with a search facility and for the establishment of an international panel to produce a implemented hyperlinks between the summary table and the set of critically evaluated rate parameters for reactions of in- data sheets, both of which can be downloaded as individual terest for atmospheric chemistry. To this end the CODATA PDF or Word ﬁles. To further enhance the accessibility of Task Group on Chemical Kinetics, under the auspices of the this updated material to the scientiﬁc community, the evalua- International Council of Scientiﬁc Unions (ICSU), was con- tion is being published as a series of articles in Atmospheric Chemistry and Physics. This article is the fourth of the series, Volume IV. Correspondence to: R. A. Cox ([email protected]) Published by Copernicus Publications on behalf of the European Geosciences Union. 4142 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Summary of recommended rate coefﬁcients for organic ical, halogen oxide reactions and photochemical processes. halogen reactions Chemical reactions are listed as ﬁrst reactant (usually an atom or radical) + second reactant (usually a molecule). Each The ordering of families in the Summary Table is: FO (Ap- datasheet has a unique identiﬁer: “Volume: Appendix: reac- pendix 1), ClO (Appendix 2), BrO (Appendix 3) and IO x x x tion number”. For example, the ﬁrst reaction in the summary (Appendix 4). The reactions are numbered sequentially for sheet below refers to Datasheet “IV.A1.1”. Photochemical the whole Volume. Within each family, reactions are listed in 3 1 reactions are listed at the end of each family section. the order: O( P), O( D), halogen atom, HO radical, NO rad- Table 1. Summary of recommended rate coefﬁcients for organic halogen reactions Reaction k Temp. dependence of Temp. 3 −1 −1 a 3 −1 −1 a number Reaction cm molecule s 1log k k/cm molecule s range/K 1(E/R)/K FO Reactions - based on data sheets in Appendix 1, and on the IUPAC website updated in 2005. 1 3 −11 1 O( D) + COF → O( P) + COF 5.2× 10 2 2 −11 → other products 2.2× 10 −11 overall 7.4× 10 ±0.3 1 3 −11 2 O( D) + CH F→ O( P) + CH F 2.7× 10 3 3 −10 → other products 1.2× 10 −10 overall 1.5× 10 ±0.15 1 3 −11 3 O( D) + CH F → O( P) + CH F 3.6× 10 2 2 2 2 −11 → other products 1.5× 10 −11 overall 5.1× 10 ±0.3 1 3 −12 4 O( D) + CHF → O( P) + CHF 8.2× 10 3 3 −13 → other products 9.1× 10 −12 overall 9.1× 10 ±0.15 1 3 −11 5 O( D) + CH CH F→ O( P) + CH CH F 4.7× 10 3 2 3 2 −10 → other products 2.1× 10 −10 overall 2.6× 10 ±0.3 1 3 −10 6 O( D) + CH CHF → O( P) + CH CHF 1.1× 10 3 2 3 2 −11 → other products 9.2× 10 −10 overall 2.0× 10 ±0.3 1 3 7 O( D) + CH CF → O( P) + CH CF 3 3 3 3 −11 → other products 5.8× 10 ±0.5 1 3 −11 8 O( D) + CH FCF → O( P) + CH FCF 4.6× 10 2 3 2 3 −12 → other products 3.0× 10 −11 overall 4.9× 10 ±0.3 1 3 −10 9 O( D) + CHF CF → O( P) + CHF CF 1.0× 10 2 3 2 3 −11 → other products 1.8× 10 −10 overall 1.2× 10 ±0.3 −14 −12 10 HO + CH F→ H O + CH F 2.1× 10 ± 0.15 1.9× 10 exp(-1350/T ) 240-300 ±400 3 2 2 −14 −12 11 HO + CH F → H O + CHF 1.1× 10 ± 0.10 2.3× 10 exp(-1590/T ) 220-300 ±200 2 2 2 2 −16 −13 12 HO + CHF → H O + CF 2.7× 10 ± 0.2 6.9× 10 exp(-2340/T ) 250-300 ±300 3 2 3 −18 13 HO + CF → HOF + CF < 2× 10 4 3 −13 14 HO + CH CH F→ H O + CH CHF 1.8× 10 3 2 2 3 −14 → H O + CH CH F 3.2× 10 2 2 2 −13 −12 overall 2.1× 10 ± 0.2 2.7× 10 exp(-765/T ) 210-300 ±300 15 HO + CH CHF → H O + CH CHF 3 2 2 2 2 → H O + CH CF 2 3 2 −14 +0.10 −12 +200 overall 3.6× 10 1.25× 10 exp(-1070/T ) 210-300 −0.20 −400 −15 −13 16 HO + CH CF → H O + CH CF 1.2× 10 ± 0.15 9.2× 10 exp(-1970/T ) 220-300 ±300 3 3 2 2 3 −13 −12 17 HO + CH FCH F→ H O + CH FCHF 1.0× 10 ± 0.3 1.5× 10 exp(-800/T ) 210-300 ±200 2 2 2 2 18 HO + CH FCHF → H O + CH FCF 2 2 2 2 2 → H O + CHFCHF 2 2 −14 −12 overall 1.5× 10 ± 0.2 3.3× 10 exp(-1610/T ) 270-330 ±300 −15 −13 19 HO + CH FCF → H O + CHFCF 4.6× 10 ± 0.2 4.9× 10 exp(-1395/T ) 220-300 ±300 2 3 2 3 −15 −12 20 HO + CHF CHF → H O + CF CHF 6.1× 10 ± 0.2 1.4× 10 exp(-1620/T ) 290-360 ±300 2 2 2 2 2 −15 −13 21 HO + CHF CF → H O + CF CF 1.9× 10 ± 0.2 4.4× 10 exp(-1630/T ) 220-300 ±300 2 3 2 2 3 22 HO + CHF CF CH F→ H O + CHF CF CHF 2 2 2 2 2 2 → H O + CF CF CH F 2 2 2 2 −15 −12 overall 7.7× 10 ± 0.3 2.2× 10 exp(-1685/T ) 285-365 ±300 −15 −13 23 HO + CF CF CH F→ H O + CF CF CHF 6.5× 10 ± 0.3 2.6× 10 exp(-1100/T ) 250-320 ±400 3 2 2 2 3 2 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4143 Reaction k Temp. dependence of Temp. 3 −1 −1 a 3 −1 −1 a number Reaction cm molecule s 1log k k/cm molecule s range/K 1(E/R)/K 24 HO + CF CHFCHF → H O + CF CFCHF 3 2 2 3 2 → H O + CF CHFCF 2 3 2 −15 −12 overall 5.0× 10 ± 0.3 1.4× 10 exp(-1680/T ) 290-380 ±300 −16 −12 25 HO + CF CH CF → H O + CF CHCF 3.3× 10 ± 0.3 1.3× 10 exp(-2465/T ) 270-340 ±400 3 2 3 2 3 3 −15 −13 26 HO + CF CHFCF → H O + CF CFCF 1.4× 10 ± 0.2 5.3× 10 exp(-1770/T ) 250-380 ±300 3 3 2 3 3 −15 −12 27 HO + CHF OCHF → H O + CHF OCF 2.2× 10 ± 0.1 1.9× 10 exp(-2020/T ) 270-460 ±300 2 2 2 2 2 −14 28 HO + HCOF→ H O + FCO < 1× 10 29 HO + CHF CHO→ H O + CHF CO 2 2 2 → H O + CF CHO 2 2 −12 overall 1.6× 10 ± 0.2 −13 30 HO + CF CHO→ H O + CF CO 5.8× 10 ± 0.2 3 2 3 −13 −13 31 HO + CF COOH→ products 1.3× 10 ± 0.1 1.3× 10 280-350 1log k =±0.1 32 HO + CH FO → O + CH FO H See data sheet 2 2 2 2 2 2 → O + HCOF + H O 2 2 33 HO + CF O → CF O H + O no recommendation 2 3 2 3 2 2 → C(O)F + HOF + O 2 2 −12 34 HO + CF CHFO → O + CF CHFO H 4.3× 10 ± 0.2 2 3 2 2 3 2 → O + CF C(O)F + H O 2 3 2 −12 −13 overall 4.3× 10 ± 0.2 2.0× 10 exp(910)/T ) 210-365 ±300 35 HO + CF CF O → O + CF CF O H 2 3 2 2 2 3 2 2 → O + CF C(O)F + HOF 2 3 −12 overall 1.2× 10 ± 0.5 −16 36 FO + CO→ products < 6× 10 −15 37 FO + CH → products < 4.1× 10 2 4 −29 −29 −4.7 38 CF + O + M→ CF O + M 2.2× 10 [N ] (k ) ± 0.1 2.2× 10 (T /300) [N ] 230-380 1n =±1.5 3 2 3 2 2 0 2 −12 −12 4× 10 (k ) ± 0.3 4× 10 200-300 1n =±1.5 F = 0.39 F = 0.39 c c −18 −10 39 CF O + O → COF + FO < 1× 10 < 1× 10 exp(-5600/T ) 250-370 3 2 2 2 −14 −12 40 CF O + O → CF O + O 1.8× 10 ±1 2× 10 exp(-1400/T ) 250-370 ±600 3 3 3 2 2 −17 −12 41 CF O + H O→ CF OH + HO < 2× 10 < 3× 10 exp(-3600/T ) 250-380 3 2 3 −11 −11 42 CF O + NO→ COF + FNO 5.4× 10 ± 0.1 3.7× 10 exp(110/T ) 230-390 ±100 3 2 −14 −12 43 CF O + CH → CF OH + CH 2.2× 10 ± 0.1 2.6× 10 exp(-1420/T ) 230-380 ±200 3 4 3 3 −12 −12 44 CF O + C H → CF OH + C H 1.3× 10 ± 0.1 4.9× 10 exp(-400/T ) 230-360 ±200 3 2 6 3 2 5 45 CH FO + O → HCOF + HO See data sheet 2 2 2 46 CH FO + M→ HCOF + H + M See data sheet 47 CH CF O + O → products See data sheet 3 2 2 48 CH CF O + M→ CH + COF + M See data sheet 3 2 3 2 49 CH FCHFO + O → CH FCOF + HO See data sheet 2 2 2 2 50 CH FCHFO + M→ CH F + HCOF + M See data sheet 2 2 51 CF CHFO + O → CF COF + HO See data sheet 3 2 3 2 52 CF CHFO + M→ CF + HCOF + M See data sheet 3 3 53 CF CF O + O → products See data sheet 3 2 2 54 CF CF O + M→ CF + CF O + M See data sheet 3 2 3 2 −11 55 CH FO + NO→ CH FO + NO 1.3× 10 ± 0.3 2 2 2 2 −11 56 CHF O + NO→ CHF O + NO 1.3× 10 ± 0.3 2 2 2 2 −11 −11 −1.2 57 CF O + NO→ CF O + NO 1.6× 10 ± 0.1 1.6× 10 exp(T /298) 230-430 1n=±0.5 3 2 3 2 −12 58 CH FCHFO + NO > 9× 10 2 2 → CH FCHFO + NO 2 2 −11 59 CHF CF O + NO→ CHF CF O + NO > 1× 10 2 2 2 2 2 2 −11 60 CF CHFO + NO→ CF CHFO + NO 1.3× 10 ±0.2 3 2 3 2 −11 61 CF CF O + NO→ CF CF O + NO > 1× 10 3 2 2 3 2 2 −29 −29 −9 62 CF O + NO + M→ CF O NO + M 5.6× 10 [N ] (k ) ±0.2 5.6× 10 (T /298) [N ] 260-300 1n=±3 3 2 2 3 2 2 2 0 2 −12 −12 −0.67 7.7× 10 (k ) ±0.2 7.7× 10 (T /298) 260-300 1n=±0.5 F =0.31 F =0.31 260-300 c c −19 −1 −5 63 CF O NO + M→ CF O + NO + M 4.5× 10 [N ] (k /s ) ±0.3 2.5× 10 exp(-9430/T )[N ] 260-300 ±250 3 2 2 3 2 2 2 0 2 −2 −1 16 6.0× 10 (k /s ) ±0.3 1.5× 10 exp(-11940/T ) 260-300 ±250 F =0.31 F =0.31 260-300 c c 64 CH FO + CH FO 2 2 2 2 → CH FOH + HC(O)F + O 2 2 −12 → 2CH FO + O 2.6× 10 ±0.3 2 2 −12 −13 overall 2.6× 10 ±0.3 2.5× 10 (exp(700/T ) 220-380±300 65 CHF O + CHF O 2 2 2 2 → CHF OH + C(O)F + O 2 2 2 → 2CH FO + O See data sheet 2 2 −12 overall (2.5-5.0)× 10 −12 66 CF O + CF O → 2CF O + O 1.5× 10 ±0.3 3 2 3 2 3 2 67 CF O + CF CHFO 3 2 3 2 → CF OH + CF COF + O 3 3 2 → CF O + CF CHFO + O 3 3 2 −12 overall 8× 10 ±0.5 68 CHF CF O + CHF CF O 2 2 2 2 2 2 → CHF CF O + CHF CF O + O no recommendation 2 2 2 2 2 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4144 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Reaction k Temp. dependence of Temp. 3 −1 −1 a 3 −1 −1 a number Reaction cm molecule s 1log k k/cm molecule s range/K 1 (E/R)/K 69 CF CHFO + CF CHFO 3 2 3 2 −13 → CF CHFOH + CF COF + O 3.3× 10 3 3 2 −12 → 2 CF CHFO + O 4.4× 10 3 2 −12 −13 overall 4.7× 10 ±0.3 6.2× 10 exp(605/T ) 210-375 ±200 70 CF CF O + CF CF O no recommendation 3 2 2 3 2 2 → 2 CF CF O + O 3 2 2 Data for the following Photochemical Reactions is based on data sheets on the IUPAC website updated in 2005 71 HC(O)F + hν → products 72 C(O)F + hν → products 73 CF CHO + hν → products 74 CF COF + hν → products ClO Reactions - based on data sheets in Appendix 2, and on the IUPAC website updated in 2005 1 3 −11 75 O( D) + CHF Cl→ O( P) + CHF Cl 2.8× 10 2 2 −11 → ClO + CHF 5.5× 10 −11 → other products 1.7× 10 −10 −10 overall 1.0× 10 ±0.1 1× 10 170-350 1logk=±0.1 1 −10 76 O( D) + CHFCl → ClO + CHFCl 1.4× 10 −11 → other products 5.0× 10 −10 −10 overall 1.9× 10 ±0.3 1.9× 10 180-350 1logk=±0.3 1 3 −11 77 O( D) + CH CF Cl→ O( P) + CH CF Cl 5.7× 10 3 2 3 2 −10 → other products 1.6× 10 −10 overall 2.2× 10 ±0.3 1 3 −11 78 O( D) + CH CFCl → O( P) + CH CFCl 8.1× 10 3 2 3 2 −10 → other products 1.8× 10 −10 overall 2.6× 10 ±0.3 1 3 −11 79 O( D) + CH ClCF → O( P) + CH ClCF 2.4× 10 2 3 2 3 −11 → other products 9.6× 10 −10 overall 1.2× 10 ±0.3 1 3 −10 80 O( D) + CH ClCF Cl→ O( P) + CH ClCF Cl 1.6× 10 ±0.5 2 2 2 2 → other products 1 3 −11 81 O( D) + CHFClCF → O( P) + CHFClCF 2.7× 10 3 3 −11 → other products 5.9× 10 −11 overall 8.6× 10 ±0.3 1 3 −11 82 O( D) + CHCl CF → O( P) + CHCl CF 4.2× 10 2 3 2 3 −10 → other products 1.6× 10 −10 overall 2.0× 10 ±0.3 1 −10 83 O( D) + CF Cl → ClO + CF Cl 1.2× 10 2 2 2 3 −11 → O( P) + CF Cl 2.4× 10 2 2 −10 −10 overall 1.4× 10 ±0.1 1.4× 10 170-350 1logk=±0.1 1 −10 84 O( D) + CFCl → ClO + CFCl 2.0× 10 3 2 3 −11 → O( P) + CFCl 3.0× 10 −10 −10 overall 2.3× 10 ±0.1 2.3× 10 170-350 1logk=±0.1 1 −10 85 O( D) + CCl → ClO + CCl 2.9× 10 4 3 3 −11 → O( P) + CCl 4.0× 10 −10 −10 overall 3.3× 10 ±0.1 3.3× 10 200-350 1logk=±0.1 1 3 −10 86 O( D) + COFCl→ O( P) + COFCl 1.9× 10 ±0.3 1 3 87 O( D) + COCl → O( P) + COCl See data sheet 2 2 → O( P) + Cl + CO See data sheet −10 → other products 1.8× 10 −10 −10 overall 2.2× 10 ±0.1 2.0× 10 exp(25/T ) 190-430 ±25 −13 −12 88 Cl + HC(O)Cl→ HCl + ClCO 7.5× 10 ±0.1 8.1× 10 exp(-710/T ) 220-330 ±150 −11 89 Cl + CH OCl→ Cl + CH O 5.2× 10 3 2 3 −12 → HCl + CH OCl 9.15× 10 −11 overall 6.1× 10 ±0.1 −13 −12 90 Cl + CH F→ HCl + CH F 3.5× 10 ±0.15 4.0× 10 exp(-730/T ) 240-370 ±400 3 2 −13 −11 91 Cl + CH Cl→ HCl + CH Cl 4.8× 10 ±0.1 2.3× 10 exp(-1150/T ) 220-360 ±200 3 2 −14 −12 92 Cl + CH F → HCl + CHF 5.0× 10 ±0.5 7.0× 10 exp(-1470/T ) 280-370 ±500 2 2 2 −13 −12 93 Cl + CH FCl→ HCl + CHFCl 1.1× 10 ±0.3 7.0× 10 exp(-1230/T ) 270-370 ±500 −13 −12 94 Cl + CH Cl → HCl + CHCl 3.4× 10 ±0.1 5.9× 10 exp(-850/T ) 220-400 ±200 2 2 2 −15 −12 95 Cl + CHF Cl→ HCl + CF Cl 1.7× 10 ±0.15 5.9× 10 exp(-2430/T ) 290-430 ±400 2 2 −14 −12 96 Cl + CHFCl → HCl + CFCl 2.0× 10 ±0.2 5.5× 10 exp(-1675/T ) 290-430 ±400 2 2 −13 −12 97 Cl + CHCl → HCl + CCl 1.1× 10 ±0.2 2.4× 10 exp(-920/T ) 220-500 ±400 3 3 −12 −11 98 Cl + CH CH F→ HCl + CH CHF 6.5× 10 ±0.3 1.0× 10 exp(-130/T ) 280-370 ±500 3 2 3 −13 −12 → HCl + CH CH F 7.4× 10 ±0.3 8.3× 10 exp(-720/T ) 280-370 ±500 2 2 −13 −12 99 Cl + CH CHF → HCl + CH CF 2.5× 10 ±0.15 6.3× 10 exp(-965/T ) 280-360 ±500 3 2 3 2 −15 −12 → HCl + CH CHF 2.3× 10 ±0.5 7.0× 10 exp(-2400/T ) 280-360 ±500 2 2 −13 −11 100 Cl + CH FCH F→ HCl + CH FCHF 7.0× 10 ±0.2 2.5× 10 exp(-1065/T ) 280-360 ±400 2 2 2 −17 −12 101 Cl + CH CF → HCl + CH CF 2.6× 10 ±0.5 6.9× 10 exp(-3720/T ) 280-370 ±500 3 3 2 3 −14 −12 102 Cl + CH FCHF → HCl + CH FCF 2.5× 10 ±0.5 3.3× 10 exp(-1450/T ) 280-370 ±500 2 2 2 2 −14 −12 → HCl + CHFCHF 2.5× 10 ±0.5 4.6× 10 exp(-1560/T ) 280-370 ±500 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4145 Reaction k Temp. dependence of Temp. 3 −1 −1 a 3 −1 −1 a number Reaction cm molecule s 1log k k/cm molecule s range/K 1 (E/R)/K −16 −12 103 Cl + CH CF Cl→ HCl + CH CF Cl 4.1× 10 ±0.15 1.4× 10 exp(-2420/T ) 296-440 ±500 3 2 2 2 −15 −12 104 Cl + CH CFCl → HCl + CH CFCl 2.1× 10 ±0.1 1.7× 10 exp(-2000/T ) 290-380 ±300 3 2 2 2 −15 −12 105 Cl + CH CCl → HCl + CH CCl 7× 10 ±0.2 2.8× 10 exp(-1790/T ) 290-420 ±400 3 3 2 3 −15 −12 106 Cl + CH FCF → HCl + CHFCF 1.5× 10 ±0.1 3.4× 10 exp(-2300/T ) 299-430 ±500 2 3 3 −15 −12 107 Cl + CHF CHF → HCl + CF CHF 2.2× 10 ±0.2 7.9× 10 exp(-2440/T ) 280-360 ±500 2 2 2 2 −16 108 Cl + CHF CF → HCl + CF CF 2.5× 10 ±0.2 2 3 2 3 −15 −12 109 Cl + CHFClCF → HCl + CFClCF 2.7× 10 ±0.1 1.1× 10 exp(-1800/T ) 270-380 ±500 3 3 −14 −12 110 Cl + CHCl CF → HCl + CCl CF 1.2× 10 ±0.1 4.4× 10 exp(-1740/T ) 270-380 ±500 2 3 2 3 −14 −12 111 HO + CH Cl→ H O + CH Cl 3.6× 10 ±0.10 2.1× 10 exp(-1210/T ) 220-300 ±200 3 2 2 −14 −12 112 HO + CH FCl→ H O + CHFCl 3.9× 10 ±0.1 1.6× 10 exp(-1105/T ) 240-300 ±200 2 2 −13 −12 113 HO + CH Cl → H O + CHCl 1.0× 10 ±0.10 1.8× 10 exp(-860/T ) 210-400 ±150 2 2 2 2 −15 −13 114 HO + CHF Cl→ H O + CF Cl 4.7× 10 ±0.08 7.9× 10 exp(-1530/T ) 240-300 ±150 2 2 2 −14 −12 115 HO + CHFCl → H O + CFCl 2.9× 10 ±0.1 1.04× 10 exp(-1065/T ) 240-300 ±200 2 2 2 −13 −12 116 HO + CHCl → H O + CCl 1.05× 10 ±0.10 1.8× 10 exp(-850/T ) 240-300 ±300 3 2 3 −18 −12 117 HO + CF Cl → HOCl + CF Cl < 7× 10 < 1× 10 exp(-3540/T ) 250-480 2 2 2 −18 −12 118 HO + CFCl → HOCl + CFCl < 5× 10 < 1× 10 exp(-3650/T ) 250-480 3 2 −16 −12 119 HO + CCl → HOCl + CCl < 5× 10 < 1× 10 exp(-2260/T ) 250-300 4 3 −12 −13 120 HO + C HCl → products 2.0× 10 ±0.10 3.0× 10 exp(565/T ) 230-300 ±200 2 3 −13 −12 121 HO + C Cl → products 1.6× 10 ±0.10 3.5× 10 exp(-920/T ) 290-420 ±300 2 4 −15 −13 122 HO + CH CF Cl→ H O + CH CF Cl 3.0× 10 ±0.10 8.5× 10 exp(-1685/T ) 220-300 ±200 3 2 2 2 2 −15 −13 123 HO + CH CFCl → H O + CH CFCl 5.8× 10 ±0.10 8.1× 10 exp(-1470/T ) 220-300 ±200 3 2 2 2 2 −15 −12 124 HO + CH CCl → H O + CH CCl 9.5× 10 ±0.10 1.2× 10 exp(-1440/T ) 240-300 ±200 3 3 2 2 3 −14 −13 125 HO + CH ClCF → H O + CHClCF 1.4× 10 ±0.15 5.6× 10 exp(-1100/T ) 260-380 ±200 2 3 2 3 −14 −12 126 HO + CH ClCF Cl→ H O + CHClCF Cl 1.7× 10 ±0.15 3.5× 10 exp(-1585/T ) 250-350 ±300 2 2 2 2 −15 −13 127 HO + CHFClCF → H O + CFClCF 8.7× 10 ±0.20 3.5× 10 exp(-1105/T ) 210-300 ±300 3 2 3 −14 −13 128 HO + CHCl CF → H O + CCl CF 3.6× 10 ±0.10 6.6× 10 exp(-870/T ) 210-300 ±200 2 3 2 2 3 −14 −13 129 HO + CHFClCF Cl→ H O + CFClCF Cl 1.2× 10 ±0.3 8.4× 10 exp(-1255/T ) 290-460 ±400 2 2 2 −14 −13 130 HO + CHCl CF Cl→ H O + CCl CF Cl 5.1× 10 ±0.2 8.1× 10 exp(-825/T ) 270-340 ±200 2 2 2 2 2 −14 −13 131 HO + CHFClCFCl → H O + CFClCFCl 1.6× 10 ±0.3 5.8× 10 exp(-1065/T ) 270-340 ±400 2 2 2 −14 −12 132 HO + CHCl CF CF → H O + CCl CF CF 2.5× 10 ±0.15 1.1× 10 exp(-1130/T ) 270-400 ±300 2 2 3 2 2 2 3 −15 −13 133 HO + CHFClCF CF Cl→ H O + CFClCF CF Cl 8.9× 10 ±0.10 5.5× 10 exp(-1230/T ) 290-400 ±300 2 2 2 2 2 −15 −13 134 HO + CH CF CFCl → H O + CH CF CFCl 2.4× 10 ±0.3 7.0× 10 exp(-1690/T ) 290-370 ±300 3 2 2 2 2 2 2 −13 135 HO + HC(O)Cl→ H O + ClCO < 5× 10 −13 −12 136 HO + CH OCl→ products 7.2× 10 ±0.3 2.4× 10 exp(-360/T ) 250-350 ±300 −15 137 HO + COCl → products < 5× 10 138 HO + CH ClCHO→ H O + CH ClCO 2 2 2 → H O + CHClCHO −12 overall 3.1× 10 ±0.15 139 HO + CHFClCHO→ H O + CHFClCO → H O + CFClCHO −12 overall 2.1× 10 ±0.15 140 HO + CHCl CHO→ H O + CHCl CO 2 2 2 → H O + CCl CHO 2 2 −12 overall 2.4× 10 ±0.15 −13 141 HO + CF ClCHO→ H O + CF ClCO 8.2× 10 ±0.25 2 2 2 −12 142 HO + CFCl CHO→ H O + CFCl CO 1.2× 10 ±0.15 2 2 2 −13 −12 143 HO + CCl CHO→ H O + CCl CO 8.0× 10 ±0.15 1.8× 10 exp(-240/T ) 230-420 ±200 3 2 3 −14 144 HO + CH COCl→ H O + CH COCl 6.8× 10 ±0.3 3 2 2 145 HO + CHF OCHClCF → H O + CHF OCClCF 2 3 2 2 3 → H O + CF OCHClCF 2 2 3 −14 −12 overall 1.5× 10 ±0.10 1.1× 10 exp(-1280/T ) 250-430 ±250 146 HO + CHF OCF CHFCl→ H O + CHF OCF CFCl 2 2 2 2 2 → H O + CF OCF CHFCl 2 2 2 −14 −13 overall 1.2× 10 ±0.10 7.5× 10 exp(-1230/T ) 250-430 ±150 −12 147 HO + CF CCl O → O + CF CCl O H 1.9× 10 ±0.3 2 3 2 2 2 3 2 2 148 HO + CH ClO → CH ClO H + O 2 2 2 2 2 2 → HC(O)Cl + H O + O 2 2 −12 −13 overall 5.0× 10 ±0.3 3.2× 10 exp(820/T ) 250-600 ±300 149 HO + CHCl O → CHCl O H + O 2 2 2 2 2 2 −12 → C(O)Cl + H O + O 4.1× 10 2 2 2 −12 → HC(O)Cl + HOCl + O 1.8× 10 −12 −13 overall 5.9× 10 ±0.3 5.6× 10 exp(700/T ) 280-440 ±300 150 HO + CF ClO → O + CF ClO H 2 2 2 2 2 2 → O + COF + HOCl 2 2 → O + FCOCl + HOF −12 overall 3.4× 10 ±0.5 151 HO + CCl O → CCl O H + O 2 3 2 3 2 2 −12 → C(O)Cl + HOCl + O 5.1× 10 2 2 −12 −13 overall 5.1× 10 ±0.3 4.7× 10 exp(710/T ) 280-440 ±300 152 HO + CFCl CH O → O + CFCl CH O H 2 2 2 2 2 2 2 2 → O + CFCl CHO + H O 2 2 2 −12 overall 9.2× 10 ±0.5 153 HO + CF ClCH O → O + CF ClCH O H 2 2 2 2 2 2 2 2 → O + CF ClCHO + H O 2 2 2 −12 overall 6.8× 10 ±0.5 www.atmos-chem-phys.net/8/4141/2008/ Atmos. 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Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Reaction k Temp. dependence of Temp. 3 −1 −1 a 3 −1 −1 a number Reaction cm molecule s 1log k k/cm molecule s range/K 1(E/R)/K −16 −13 154 NO + C HCl → products 3.5× 10 ±0.2 3.2× 10 exp(-2030/T ) 270-370 ±500 3 2 3 −16 155 NO + C Cl → products < 1× 10 3 2 4 −12 156 ClO + CH O → ClOO + CH O 1.6× 10 See data sheet 3 2 3 → OClO + CH O → HCHO + HCl +O → CH Cl + O 3 3 −13 → CH OCl + O 3.3× 10 See data sheet 3 2 −12 −12 overall 2.2× 10 ±0.15 2.4× 10 exp(-20/T ) 220-360 ±200 −29 −29 −5 157 CF Cl + O + M→ CF ClO + M 1.4× 10 [N ] (k ) ±0.5 1.4× 10 (T /300) [N ] 200-300 1n=±3 2 2 2 2 2 0 2 −12 −12 −0.6 7× 10 (k ) ±0.5 7× 10 (T /298) 200-300 1n=±0.5 F = 0.4 F = 0.4 200-300 c c −30 −30 −6 158 CFCl + O + M→ CFCl O + M 6× 10 [N ] (k ) ±0.3 6× 10 (T /298) [N ] 230-380 1n=±3 2 2 2 2 2 0 2 −12 −12 9× 10 (k ) ±0.3 9× 10 230-300 1n=±1 F ≈ 0.4 F ≈ 0.4 230-380 c c −30 −30 −6.2 159 CCl + O + M→ CCl O + M 1.1× 10 [N ] (k ) ±0.2 1.1× 10 (T /300) [N ] 230-350 1n=±1 3 2 3 2 2 0 2 −12 −12 −1.4 5.2× 10 (k ) ±0.3 5.2× 10 (T /300) 260-350 1n=±1 F = 0.35 F = 0.35 230-350 c c 160 CHFClO + O → COFCl + HO See data sheet 2 2 161 CHFClO + M→ HCOF + Cl + M See data sheet 162 CF ClO + O → products See data sheet 2 2 163 CF ClO + M→ COF + Cl + M See data sheet 2 2 164 CFCl O + O → products See data sheet 2 2 165 CFCl O + M→ COFCl + Cl + M See data sheet 166 CCl O + M→ COCl + Cl See data sheet 3 2 167 CF ClCH O + O → CF ClCHO + HO See data sheet 2 2 2 2 2 168 CF ClCH O + M→ CF Cl + HCHO + M See data sheet 2 2 2 169 CFCl CH O + O → CFCl CHO + HO See data sheet 2 2 2 2 2 170 CFCl CH O + M→ CFCl + HCHO + M See data sheet 2 2 2 171 CF CFClO + O → products See data sheet 3 2 172 CF CFClO + M→ CF COF + Cl + M See data sheet 3 3 173 CF CCl O + O → products See data sheet 3 2 2 174 CF CCl O + M→ CF COCl + Cl + M See data sheet 3 2 3 175 CF CF CCl O + O → products See data sheet 3 2 2 2 176 CF CF CCl O + M→ CF CF COCl + Cl + M See data sheet 3 2 2 3 2 177 CF ClCF CFClO + O → products See data sheet 2 2 2 178 CF ClCF CFClO + M→ CF ClCF COF + Cl + M See data sheet 2 2 2 2 179 CH ClO + O → HCOCl + HO See data sheet 2 2 2 180 CH ClO + M→ HCO + HCl + M See data sheet 181 CH CHClO + O → CH COCl + HO See data sheet 3 2 3 2 182 CH CHClO + M→ CH CO + HCl + M See data sheet 3 3 183 HOCH CHClO + O → HOCH COCl + HO See data sheet 2 2 2 2 184 HOCH CHClO + M→ CH OH + HCOCl + M See data sheet 2 2 185 HOCHClCH O + O → HOCHClCHO + HO See data sheet 2 2 2 186 HOCHClCH O + M→ CHClOH + HCHO + M See data sheet 187 CH CCl O + O → products See data sheet 3 2 2 188 CH CCl O + M→ CH COCl + Cl + M See data sheet 3 2 3 189 CCl CH O + O → CCl CHO + HO See data sheet 3 2 2 3 2 190 CCl CH O + M→ CCl + HCHO + M See data sheet 3 2 3 191 CCl CCl O + O → products See data sheet 3 2 2 192 CCl CCl O + M→ CCl COCl + Cl + M See data sheet 3 2 3 −11 193 CH ClO + NO→ CH ClO + NO 1.9× 10 ±0.3 2 2 2 2 −11 194 CHFClO + NO→ CHFClO + NO 1.3× 10 ±0.3 2 2 −11 −11 −1.5 195 CF ClO + NO→ CF ClO + NO 1.5× 10 ±0.2 1.5× 10 (T /298) 230-430 1n=±0.5 2 2 2 2 −11 −11 −1.3 196 CFCl O + NO→ CFCl O + NO 1.5× 10 ±0.2 1.5× 10 (T /298) 230-430 1n=±0.5 2 2 2 2 −11 −11 −1.0 197 CCl O + NO→ CCl O + NO 1.8× 10 ±0.2 1.8× 10 (T /298) 230-430 1n=±0.5 3 2 3 2 −11 −11 −1.8 198 CH CFClO + NO→ CH CFClO + NO 2.0× 10 ±0.3 2.0× 10 (T /298) 260-320 1n=±0.5 3 2 3 2 −11 199 CF ClCH O + NO→ CF ClCH O + NO 1.2× 10 ±0.3 2 2 2 2 2 2 −11 −11 −1.5 200 CFCl CH O + NO + M→ CFCl CH O + NO 1.3× 10 ±0.2 1.3× 10 (T /298) 260-320 1n=±0.5 2 2 2 2 2 2 −11 201 CF CCl O + NO→ CF CCl O + NO 1.8× 10 ±0.3 3 2 2 3 2 2 −12 202 CH ClCH O + NO→ CH ClCH O + NO 9.7× 10 ±0.3 2 2 2 2 2 2 −29 −29 −6.2 203 CF ClO + NO + M→ CF ClO NO + M 5.0× 10 [N ] (k ) ±0.3 5.0× 10 (T /298) [N ] 250-320 1n=±2 2 2 2 2 2 2 2 0 2 −12 −12 −0.7 6.3× 10 (k ) ±0.3 6.3× 10 (T /298) 250-320 1n=±0.5 F =0.30 F =0.30 250-320 c c −19 −1 −3 204 CF ClO NO + M→ CF ClO + NO + M 9.0× 10 [N ] (k /s ) ±0.3 1.8× 10 exp(-10500/T ) [N ] 270-290 ±200 2 2 2 2 2 2 2 0 2 −2 −1 16 5.4× 10 (k /s ) ±0.3 1.6× 10 exp(-11990/T ) 270-290 ±200 F =0.30 F =0.30 270-290 c c −29 −29 −5.5 205 CFCl O + NO + M→ CFCl O NO + M 5.5× 10 [N ] (k ) ±0.3 5.5× 10 (T /298) [N ] 230-380 1n=±2 2 2 2 2 2 2 2 0 2 −12 −12 −0.66 8.3× 10 (k ) ±0.2 8.3× 10 (T /298) 230-380 1n=±0.5 F =0.42 F =0.42 230-380 c c −18 −1 −2 206 CFCl O NO + M→ CFCl O + NO + M 1.5× 10 [N ] (k /s ) ±0.3 1.0× 10 exp(-10860/T )[N ] 260-300 ±200 2 2 2 2 2 2 2 0 2 −2 −1 16 9.6× 10 (k /s ) ±0.3 6.6× 10 exp(-12240/T ) 260-300 ±500 F =0.28 F =0.28 260-300 c c −29 −29 −6.0 207 CCl O + NO + M→ CCl O NO + M 9.2× 10 [N ] (k ) ±0.3 9.2× 10 (T /298) [N ] 230-380 1n=±2 3 2 2 3 2 2 2 0 2 −12 −12 −0.7 1.5× 10 (k ) ±0.3 1.5× 10 (T /298) 230-380 1n=±0.5 F =0.32 F =0.32 230-380 c c Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4147 Reaction k Temp. dependence of Temp. 3 −1 −1 a 3 −1 −1 a number Reaction cm molecule s 1log k k/cm molecule s range/K 1(E/R)/K −18 −1 −3 208 CCl O NO + M→ CCl O + NO + M 5.2× 10 [N ] (k /s ) ±0.3 4.3× 10 exp(-10235/T )[N ] 260-300 ±500 3 2 2 3 2 2 2 0 2 −1 16 0.29 (k /s ) ±0.3 4.8× 10 exp(-11820/T ) 260-300 ±500 F =0.32 F =0.32 260-300 c c 209 C H O + CF CCl O 2 5 2 3 2 2 −12 → CH CHO + CF CCl OH + O 3.6× 10 ±0.3 3 3 2 2 −13 → C H O + CF CCl O + O 9× 10 ±0.5 2 5 3 2 2 210 CF ClCH O + CF ClCH O 2 2 2 2 2 2 → CF ClCH OH + CF ClCHO + O 2 2 2 2 −12 → CF ClCH O + CF ClCH O + O 2.8× 10 2 2 2 2 2 −12 overall 2.8× 10 ±0.4 211 CFCl CH O + CFCl CH O 2 2 2 2 2 2 → CFCl CH OH + CFCl CHO + O 2 2 2 2 −12 → 2CFCl CH O + O 2.9× 10 2 2 2 −12 overall 2.9× 10 ±0.4 −12 212 CF CCl O + CF CCl O 3.5× 10 ±0.3 3 2 2 3 2 2 → 2CF CCl O + O 3 2 2 213 CH ClO + CH ClO 2 2 2 2 → CH ClOH + HC(O)Cl + O 2 2 −12 → 2CH ClO + O 3.5× 10 2 2 −12 −13 overall 3.5× 10 ±0.2 1.9× 10 exp(870/T ) 250-600 ±200 214 CHCl O + CHCl O See data sheet 2 2 2 2 → CHCl OH + C(O)Cl + O 2 2 2 → CHCl O + CHCl O + O 2 2 2 −12 −13 215 CCl O + CCl O → 2CCl O + O 4.0× 10 ±0.3 3.3× 10 exp(740/T ) 270-460 ±300 3 2 3 2 3 2 216 CH CHClO + CH CHClO 3 2 3 2 → CH CHClOH + CH COCl + O 3 3 2 −12 → 2CH CHClO + O 5× 10 ±0.3 3 2 overall See data sheet 217 CH ClCH O + CH ClCH O 2 2 2 2 2 2 −12 → CH ClCH OH + CH ClCHO + O 1.2× 10 2 2 2 2 −12 → 2CH ClCH O + O 2.1× 10 2 2 2 −12 −14 overall 3.3× 10 ±0.3 4.2× 10 exp(1300/T ) 220-380 ±500 −20 218 O + C HCl → products < 5× 10 3 2 3 −21 219 O + C Cl → products < 10 3 2 4 Data for the following Photochemical Reactions is based on data sheets on the IUPAC website updated in 2005 220 CH Cl + hν → products 221 CH OCl + hν → products 222 CHF Cl + hν → products 223 CF Cl + hν → products 2 2 224 CFCl + hν → products 225 CCl + hν → products 226 CH CF Cl + hν → products 3 2 227 CH CFCl + hν → products 3 2 228 CH CCl + hν → products 3 3 229 CF CHFCl + hν → products 230 CF CHCl + hν → products 3 2 231 CF ClCFCl + hν → products 2 2 232 CF ClCF Cl + hν → products 2 2 233 CF CF Cl + hν → products 3 2 234 CF CF CHCl + hν → products 3 2 2 235 CF ClCF CHFCl + hν → products 2 2 236 HCOCl + hν → products 237 COFCl + hν → products 238 COCl + hν → products 239 CF ClCHO + hν → products 240 CFCl CHO + hν → products 241 CCl CHO + hν → products 242 CF COCl + hν → products BrO Reactions - based on data sheets in Appendix 3, and on the IUPAC website updated in 2005 −14 −12 243 HO + CH Br→ H O + CH Br 2.9× 10 ±0.08 1.7× 10 exp(-1215/T ) 240-300 ±150 3 2 2 −13 −12 244 HO + CH Br → H O + CHBr 1.1× 10 ±0.15 1.5× 10 exp(-775/T ) 240-300 ±200 2 2 2 2 −14 −13 245 HO + CHF Br→ H O + CF Br 1.0× 10 ±0.10 7.9× 10 exp(-1300/T ) 230-360 ±150 2 2 2 −18 −12 246 HO + CF Br→ products < 6.0× 10 < 1× 10 exp(-3600/T ) 250-460 −17 −12 247 HO + CF ClBr→ products < 1× 10 < 1× 10 exp(-3450/T ) 250-380 −16 −12 248 HO + CF Br → products < 5.0× 10 < 1× 10 exp(-2200/T ) 250-460 2 2 −14 −12 249 HO + CF CH Br→ H O + CF CHBr 1.6× 10 ±0.2 1.4× 10 exp(-1340/T ) 280-460 ±300 3 2 2 3 −14 −13 250 HO + CF CHFBr→ H O + CF CFBr 1.7× 10 ±0.2 8.1× 10 exp(-1155/T ) 270-460 ±300 3 2 3 −14 −12 251 HO + CF CHClBr→ H O + CF CClBr 4.6× 10 ±0.20 1.2× 10 exp(-970/T ) 290-460 ±300 3 2 3 −18 −12 252 HO + CF BrCF Br→ products < 6× 10 < 1× 10 exp(-3600/T ) 250-460 2 2 −12 253 HO + CH BrO → O + CH BrO H 6.7× 10 2 2 2 2 2 2 → O + HC(O)Br + H O 2 2 −11 254 CH BrO + NO→ CH BrO + NO 1.1× 10 ±0.3 2 2 2 2 −11 255 CHBr O + NO→ CHBr O + NO 1.7× 10 ±0.3 2 2 2 2 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4148 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Reaction k Temp. dependence of Temp. 3 −1 −1 a 3 −1 −1 a number Reaction cm molecule s 1log k k/cm molecule s range/K 1(E/R)/K 256 CH BrO + CH BrO 2 2 2 2 → HC(O)Br + CH BrOH + O see data sheet 2 2 → 2CH BrO+ O 2 2 257 BrCH CH O + BrCH CH O 2 2 2 2 2 2 −12 → BrCH CH OH + BrCH CHO + O 1.7× 10 2 2 2 2 −12 → 2BrCH CH O + O 2.3× 10 2 2 2 −12 −14 overall 4.0× 10 ±0.2 6.0× 10 exp(1250/T ) 270-380 ±500 −12 258 BrO + CH O → CH O + BrOO 1.4× 10 3 2 3 −12 → HOBr + CH O 4.3× 10 2 2 −12 overall 5.7× 10 ± 0.3 Data for the following Photochemical Reactions is based on data sheets on the IUPAC website updated in 2006 259 CH Br + hν → products 260 CF Br + hν → products 261 CF ClBr + hν → products 262 CF Br + hν → products 2 2 263 CHBr + hν → products 264 CF BrCF Br + hν → products 2 2 265 CH Br + hν → products 2 2 IO Reactions – based on data data sheets in Appendix 4, and on the IUPAC website updated in 2005 −13 −12 266 HO + CH I→ H O + CH I 1.0× 10 ±0.2 4.3× 10 exp(-1120/T ) 270-430 ±500 3 2 2 −14 −11 267 HO + CF I→ products 2.6× 10 ±0.2 2.1× 10 exp(-2000/T ) 270-370 ±500 268 CH IO + CH IO → CH IOH + HC(O)I + O no recommendation 2 2 2 2 2 2 → 2CH IO + O 2 2 Data for the following Photochemical Reactions is based on data sheets on the IUPAC website updated in 2006 269 CH I + hν → products 270 CF I + hν → products 271 CH CII + hν → products 272 CH BrI + hν → products 273 CH I + hν → products 2 2 The cited uncertainty is an expanded uncertainty corresponding approximately to a 95% conﬁdence limit 2 Guide to the data sheets reactions, we have listed temperature dependences in the al- 0 −n n ternative form, k=A T or CT exp(−D/T ), where the original authors have found this to give a better ﬁt to the data. The data sheets are principally of two types: (i) those for For pressure dependent combination and dissociation reac- individual thermal reactions and (ii) those for the individual tions, generally the non-Arrhenius temperature dependence photochemical reactions. is used. This is discussed more fully in a subsequent section of this Introduction. 2.1 Thermal reactions Single temperature data are presented as such and wher- ever possible the rate coefﬁcient at, or close to, 298 K is The data sheets begin with a statement of the reactions in- quoted directly as measured by the original authors. This cluding all pathways which are considered feasible. This is means that the listed rate coefﬁcient at 298 K may differ followed by the corresponding enthalpy changes at 298 K, slightly from that calculated from the Arrhenius parameters calculated from the enthalpies of formation summarized in determined by the same authors. Rate coefﬁcients at 298 K the Thermodynamics Data Summary, which is provided on marked with an asterisk indicate that the value was calculated the IUPAC website. by extrapolation of a measured temperature range which did The available kinetic data on the reactions are summa- not include 298 K. The tables of data are supplemented by rized under two headings: (i) Absolute Rate Coefﬁcients, a series of comments summarizing the experimental details. and (ii) Relative Rate Coefﬁcients. Under these headings, The following list of abbreviations, relating to experimental we include new data which have been published since the techniques, is used in the Techniques and Comments sec- last published IUPAC evaluation as well as the data used in tions: deriving the preferred values. Under both of the headings above, the data are presented as absolute rate coefﬁcients. If A – absorption the temperature coefﬁcient has been measured, the results are AS – absorption spectroscopy given in a temperature dependent form over a stated temper- CCD – charge coupled detector ature range. For bimolecular reactions, the temperature de- CIMS – chemical ionization mass spectroscopy/spectrometric pendence is usually expressed in the normal Arrhenius form, k=A exp(−B/T ), where B=E/R. For a few bimolecular CL – chemiluminescence Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4149 CRDS – cavity ring-down spectroscopy 2.2 Conventions concerning rate coefﬁcients DF – discharge ﬂow All of the reactions in the table are elementary processes. EPR – electron paramagnetic resonance Thus the rate expression is derived from a statement of the F – ﬂow system reaction, e.g. FP – ﬂash photolysis A+ A → B+ C FTIR – Fourier transform infrared 1 d[A] d[B] d[C] − = = = k[A] . FTS – Fourier transform spectroscopy 2 dt dt dt GC – gas chromatography/gas chromatographic Note that the stoichiometric coefﬁcient for A, i.e. 2, appears HPLC – high-performance liquid chromatography in the denominator before the rate of change of [A] (which is IR – infrared equal to 2k[A] ) and as a power on the righthand side. Representations of k as a function of temperature charac- LIF – laser induced ﬂuorescence terize simple “direct” bimolecular reactions. Sometimes it is LMR – laser magnetic resonance found that k also depends on the pressure and the nature of LP – laser photolysis the bath gas. This may be an indication of complex forma- MM – molecular modulation tion during the course of the bimolecular reaction, which is MS – mass spectrometry/mass spectrometric always the case in combination reactions. In the following P – steady state photolysis sections, the representations of k which are adopted in these cases are explained. PLP – pulsed laser photolysis PR – pulse radiolysis 2.3 Treatment of combination and dissociation reactions RA – resonance absorption Unlike simple bimolecular reactions such as those consid- REMPI - resonance enhanced multiphoton ionisation ered in Sect. 3.2, combination reactions RF – resonance ﬂuorescence A+ B+ M → AB+ M RR – relative rate S – static system and the reverse dissociation reactions TDLS – tunable diode laser spectroscopy AB+ M → A+ B+ M UV – ultraviolet are composed of sequences of different types of physical and UVA – ultraviolet absorption chemical elementary processes. Their rate coefﬁcients reﬂect VUVA – vacuum ultraviolet absorption the more complicated sequential mechanism and depend on the temperature, T , and the nature and concentration of the For measurements of relative rate coefﬁcients, wherever pos- third body, [M]. In this evaluation, the combination reactions sible the comments contain the actual measured ratio of rate are described by a formal second-order rate law: coefﬁcients together with the rate coefﬁcient of the reference d[AB] = k[A][B] reaction used to calculate the absolute rate coefﬁcient listed dt in the data table. The absolute value of the rate coefﬁcient while dissociation reactions are described by a formal ﬁrst- given in the table may be different from that reported by the order rate law: original author owing to a different choice of rate coefﬁcient −d[AB] of the reference reaction. Whenever possible the reference = k[AB] dt rate data are those preferred in the present evaluation. In both cases, k depends on the temperature and on [M]. The preferred rate coefﬁcients are presented (i) at a tem- To rationalize the representations of the rate coefﬁcients perature of 298 K and (ii) in temperature dependent form used in this evaluation, we ﬁrst consider the Lindemann- over a stated temperature range. This is followed by a state- Hinshelwood reaction scheme. The combination reactions ment of the uncertainty limits in log k at 298 K and the un- follow an elementary mechanism of the form, certainty limits either in (E/R) or in n, for the mean tem- A+ B → AB (1) perature in the range. Some comments on the assignment of uncertainties are given later in this Introduction. AB → A+ B (-1) The “Comments on Preferred Values” describe how the AB + M → AB+ M (2) selection was made and give any other relevant information. The extent of the comments depends upon the present state while the dissociation reactions are characterized by: of our knowledge of the particular reaction in question. The AB+ M → AB + M (-2) data sheets are concluded with a list of the relevant refer- ences. AB + M → AB+ M (2) www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4150 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry AB → A+ B (-1) The broadening factor F depends on the ratio k /k , which 0 ∞ is proportional to [M], and can be used as a measure of “re- Assuming quasi-stationary concentrations for the highly ex- duced pressure”. The ﬁrst factors on the right-hand side rep- ∗ ∗ cited unstable species AB (i.e. that d[AB ]/dt≈0), it follows resent the Lindemann-Hinshelwood expression and the addi- that the rate coefﬁcient for the combination reaction is given tional broadening factor F , at not too high temperatures, is by: approximately given by (Troe, 1979): k [M] log F k = k ∼ log F k + k [M] −1 2 1+[log(k /k )/N] 0 ∞ while that for the dissociation reaction is given by: where log=log and N ≈ [0.75−1.27 log F ]. In this way 10 c the three quantities k , k , and F characterise the falloff 0 ∞ c −1 k = k [M] curve for the present application. −2 k + k [M] −1 2 The given approximate expression for the broadening fac- tor F was obtained from statistical unimolecular rate theory In these equations the expressions before the parentheses rep- in its simplest form (Troe, 1979). More rigorous represen- resent the rate coefﬁcients of the process initiating the reac- tations require detailed information on the potential energy tion, whereas the expressions within the parentheses denote surfaces and on the collisional energy transfer step of the re- the fraction of reaction events which, after initiation, com- action. If this information is not available, one may assume plete the reaction to products. typical behaviour and rely on the theoretical analysis given In the low pressure limit ([M] → 0) the rate coefﬁcients by Cobos and Troe (2003). For T=200–300 K and the col- are proportional to [M]; in the high pressure limit ([M] lider M=N (with a collision efﬁciency β ≈0.3), this treat- → ∞) they are independent of [M]. It is useful to express 2 c ment predicts F ≈0.49, 0.44, 0.39, and 0.35, if the reactants k in terms of the limiting low pressure and high pressure rate A and B in total have r=3, 4, 5, or 6 rotational degrees of coefﬁcients, freedom, respectively (e.g. for the reaction HO+NO , one k = lim k([M]) k = lim k([M]), 0 ∞ would have r=5 and hence F ≈0.39). It is also predicted and [M] → 0 [M] → ∞ that F , for the present applications, should be nearly tem- perature independent. Finally, more rigorous expressions for respectively. From this convention, the Lindemann- the broadening factors F are given in Cobos and Troe (2003) Hinshelwood equation is obtained which, in general do not differ from the above formula by k k more than about 10 percent. Since the special properties of o ∞ k = each reaction system may lead to some deviations from the k + k o ∞ given values of F , these should only be used for a ﬁrst orien- It follows that for combination reactions, k =k k [M]/k 0 1 2 −1 tation. Larger deviations of experimentally ﬁtted F -values and k =k , while for dissociation reactions, k =k [M] ∞ 1 0 −2 from the given “standard values”, however, may be an indi- and k =k k /k . Since detailed balancing applies, the ra- ∞ −1 −2 2 cation for inadequate falloff extrapolations to k and k . In 0 ∞ tio of the rate coefﬁcients for combination and dissociation this case, the apparent values for F , k , and k obtained c 0 ∞ at a ﬁxed T and [M] is given by the equilibrium constant by ﬁtting still can provide a satisfactory representation of the K =k k /k k . c 1 2 −1 −2 considered experimental data, in spite of the fact that inade- Starting from the high-pressure limit, the rate coefﬁcients quate values of k and k are obtained by extrapolation. 0 ∞ fall off with decreasing third body concentration [M] and If a given falloff curve is ﬁtted in different ways, changes the corresponding representation of k as a function of [M] in F require changes in the limiting k and k values. For c 0 ∞ is termed the “falloff curve” of the reaction. In practice, the purpose of this evaluation, this is irrelevant if the pre- the above Lindemann-Hinshelwood expressions do not suf- ferred k and k are used consistently together with the pre- 0 ∞ ﬁce to characterize the falloff curves completely. Because of ferred F values. If the selected F value is too large, the c c the multistep character of the collisional deactivation (k [M]) values of k and k obtained by ﬁtting the falloff expres- 0 ∞ and activation (k [M]) processes, and energy- and angular −2 sion to the experimental data are underestimated. If F is too momentum-dependencies of the association (k ) and disso- small, k and k are overestimated. However uncertainties 0 ∞ ciation (k ) steps, as well as other phenomena, the falloff −1 in F inﬂuence the ﬁtted k and k in different ways. A sim- c 0 ∞ expressions have to be modiﬁed. This can be done by includ- pler policy of ﬁtting falloff was chosen by the NASA/JPL ing a broadening factor F to the Lindemann-Hinshelwood panel (Sander et al., 2003) in putting F=0.6 and N=1. This expression (Troe, 1979): generally leads to different values of the ﬁtted k and k and 0 ∞ ! ! their temperature dependencies than derived here, although k k 1 o ∞ k experimental data over the range of atmospheric interest can k = F = k F = k F o ∞ k k o o k + k o ∞ 1+ 1+ generally be reproduced equally well. However the derived k k ∞ ∞ Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4151 k and k may differ from the true limiting rate coefﬁcients We designate the rate coefﬁcients of the individual steps as 0 ∞ and thus should be interpreted by theory only with caution. in Sect. 3.3, above: In the present evaluation, we generally follow the experi- A+ B → AB (1) mentally ﬁtted values for F , k , and k , provided F does c 0 ∞ c not differ too much from the values given above. If large AB → A+ B (-1) deviations are encountered, the experimental data are re- evaluated using the given F -values given above. AB + M → AB+ M (2) Besides the energy-transfer mechanism, i.e. Reactions (1), (-1), and (2), a second mechanism appears to be relevant for ∗ AB → C+ D (3) some reactions considered here. This is the radical-complex (or chaperon) mechanism Assuming quasi-stationary concentrations of AB (i.e. d[AB ]/dt ≈ 0), a Lindemann-Hinshelwood type of analy- A+ M → AM (3) sis leads to, d[AB] AM → A+ M (-3) = k [A][B] dt B+ AM → AB+ M (4) d[C] = k [A][B] which, in the low pressure range, leads to dt d[A] k = (k /k )k [M]. 0 3 −3 4 = −(k + k )[A][B] S D dt For some tri- and tetra-atomic adducts AB, e.g. O + O → where O and Cl + O → ClOO, this value of k may exceed that 3 2 0 from the energy-transfer mechanism and show stronger tem- k = k S 1 perature as dependencies (Luther et al., 2005). This mecha- k + k + k −1 2 3 nism may also inﬂuence high pressure experiments when k from the radical-complex mechanism exceeds k from the ∞ k k = k D 1 energy-transfer mechanism (Oum et al., 2003). In this case k + k + k −1 2 3 falloff over wide pressure ranges cannot be represented by contributions from the energy-transfer mechanism alone, in Note that since k is proportional to [M], k and k are 2 S D particular when measurements at pressures above about 10 dependent on the nature and concentration of the third body bar are taken into consideration. M, in addition to their temperature dependence. In reality, The dependence of k and k on the temperature T is rep- as for the combination and dissociation reactions, the given 0 ∞ −n resented in the form k∝T except for cases with an estab- expressions for k and k have to be extended by suitable S D lished energy barrier in the potential. We have used this form broadening factors F to account for the multistep character of temperature dependence because it usually gives a better of process (2) and the energy and angular momemtum de- ﬁt to the data over a wider range of temperature than does pendencies of processes (1), (-1) and (3). These broadening the Arrhenius expression. It should be emphasised that the factors, however, differ from those for combination and dis- chosen form of the temperature dependence is often only ad- sociation reactions. For simplicity, they are ignored in this equate over limited temperature ranges such as 200–300 K. evaluation such that k at high pressure approaches Obviously, the relevant values of n are different for k and k → k k /k D 1 3 2 k . In this evaluation, values of k are given for selected ∞ 0 examples of third bodies M, and if possible for M=N , O or 2 2 which is inversely proportional to [M]. k may also be ex- air. pressed by 2.4 Treatment of complex-forming bimolecular reactions k ≈ k k /k D D0 S S0 Bimolecular reactions may follow the “direct” pathway where k and k are the respective limiting low-pressure D0 S0 rate coefﬁcients for the formation of C+D or A+B at the con- A+ B → C+ D sidered [M]. When it is established that complex-formation is involved, this equation is used to characterize the increas- and/or involve complex formation, ing suppression of C+D formation with increasing [M]. One should also note that bimolecular reactions may have con- A+ B ⇔ AB → C+ D tributions from direct as well as complex-forming pathways ↓ M leading to identical or different products. AB www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4152 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 2.5 Photochemical reactions 2.7 Assignment of uncertainties Under the heading “reliability,” estimates have been made of The data sheets begin with a list of feasible primary pho- the absolute accuracies of the preferred values of k at 298 K tochemical transitions for wavelengths usually down to and of the preferred values of E/R over the quoted temper- 170 nm, along with the corresponding enthalpy changes at ature range. The accuracy of the preferred rate coefﬁcient at 0 K where possible or alternatively at 298 K, calculated from 298 K is quoted as the term 1log k, where 1log k=d and d is the data in the Thermodynamic Data summary. Calcu- deﬁned by the equation, logk=c±d . This is equivalent to the lated threshold wavelengths corresponding to these enthalpy statement that k is uncertain to a factor of f , where d =logf . changes are also listed, bearing in mind that the values calcu- The accuracy of the preferred value of E/R is quoted as the lated from the enthalpy changes at 298 K are not true “thresh- term 1(E/R), where 1(E/R)=g and g is deﬁned by the old values”. equation E/R=h±g. d and g are expanded uncertainties This is followed by tables which summarise the available corresponding approximately to a 95% conﬁdence limit. experimental data for: (i) absorption cross sections and (ii) For second-order rate coefﬁcients listed in this evalua- quantum yields. These data are supplemented by a series of tion, an estimate of the uncertainty at any given temperature comments. within the recommended temperature range may be obtained The next table lists the preferred absorption cross section from the equation: data and the preferred quantum yields at appropriate wave- length intervals. For absorption cross sections the intervals 1 log k(T ) = 1 log k(298 K)+ 0.4343{1E/R(1/T − 1/298)} are usually 1 nm, 5 nm or 10 nm. Any temperature depen- The assignment of these absolute uncertainties in k and E/R dence of the absorption cross sections is also given where is a subjective assessment of the evaluators. They are not de- possible. The aim in presenting these preferred data is to termined by a rigorous, statistical analysis of the database, provide a basis for calculating atmospheric photolysis rates. which is generally too limited to permit such an analy- For absorption continua the temperature dependence is often sis. Rather, the uncertainties are based on a knowledge of represented by Sulzer-Wieland type expressions (Astholz et al., 1981). Alternately a simple empirical expression of the the techniques, the difﬁculties of the experimental measure- form: log (σ /σ )=B(T -T ) is used. ments, the potential for systematic errors, and the number of 10 T 1 T 2 1 2 studies conducted and their agreement or lack thereof. Ex- The comments again describe how the preferred data were perience shows that for rate measurements of atomic and selected and include other relevant points. The photochemi- free radical reactions in the gas phase, the precision of the cal data sheets are concluded with a list of references. measurement, i.e. the reproducibility, is usually good. Thus, 2.6 Conventions concerning absorption cross sections for single studies of a particular reaction involving one tech- nique, standard deviations, or even 95% conﬁdence limits, of These are presented in the data sheets as “absorption cross ±10% or less are frequently reported in the literature. Unfor- sections per molecule, base e.” They are deﬁned according to tunately, when evaluators compare data for the same reaction the equations: studied by more than one group of investigators and involv- ing different techniques, the rate coefﬁcients often differ by I/I = exp(−σ[N]l), a factor of 2 or even more. This can only mean that one or more of the studies has involved large systematic uncer- σ = {1/([N]l)} ln(I /I), tainty which is difﬁcult to detect. This is hardly surprising since, unlike molecular reactions, it is not always possible to where I and I are the incident and transmitted light inten- study atomic and free radical reactions in isolation, and con- sities, σ is the absorption cross section per molecule (ex- sequently mechanistic and other difﬁculties frequently arise. pressed in this paper in units of cm ), [N] is the number con- On the whole, our assessment of uncertainty limits tends −3 centration of absorber (expressed in molecule cm ), and l towards the cautious side. Thus, in the case where a rate co- is the path length (expressed in cm). Other deﬁnitions and efﬁcient has been measured by a single investigation using units are frequently quoted. The closely related quantities one particular technique and is unconﬁrmed by independent “absorption coefﬁcient” and “extinction coefﬁcient” are of- work, we suggest that minimum uncertainty limits of a factor ten used, but care must be taken to avoid confusion in their of 2 are appropriate. deﬁnition. It is always necessary to know the units of con- In contrast to the usual situation for the rate coefﬁcients centration and of path length and the type of logarithm (base of thermal reactions, where intercomparison of results of a e or base 10) corresponding to the deﬁnition. To convert an number of independent studies permits a realistic assessment absorption cross section to the equivalent Naperian (base e) of reliability, for many photochemical processes there is a −1 absorption coefﬁcient (expressed in cm ) of a gas at a pres- scarcity of reliable data. Thus, we do not feel justiﬁed at sure of one standard atmosphere and temperature of 273 K, present in assigning uncertainty limits to the parameters re- 2 19 multiply the value of σ in cm by 2.69×10 . ported for the photochemical reactions. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4153 Acknowledgements. The Chairman and members of the Commit- Atkinson, R., Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, J. tee wish to express their appreciation to I.U.P.A.C. for the ﬁnancial A., Rossi, M. J., and Troe, J.: Evaluated Kinetic and Photochem- help which facilitated the preparation of this evaluation. We also ac- ical Data for Atmospheric Chemistry: Supplement VII, IUPAC knowledge ﬁnancial support from the following organisations: EU Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Framework Program 6, ACCENT network of excellence; Univer- Chemistry, J. Phys. Chem. Ref. Data, 28, 191–393, 1999. sity of California Agricultural Experiment Station; the UK Natural Atkinson, R., Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, J. Environmental Research Council; the Standard Reference Data A., Rossi, M. J., and Troe, J.: Evaluated Kinetic and Photochem- Program (N.I.S.T); the Fonds National Suisse de la Recherche Sci- ical Data for Atmospheric Chemistry, Supplement VIII, IUPAC entiﬁque (F.N.S.R.S.) and the Ofﬁce Fed ´ eral ´ de l’Education et de Subcommittee on Gas Kinetic Data Evaluation for Atmospheric la Science, Ford Motor Company, and the Deutsche Forschungs- Chemistry, J. Phys. Chem. Ref. Data, J. Phys. Chem. Ref. Data, gemeinschaft (SFB 357). We also thank B. Cox for her work in 29, 167–266, 2000. preparing and editing the manuscript. Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, J. A., Troe, J., and Watson, R. T.: Evaluated Kinetic and Photochemical Data Edited by: W. T. Sturges for Atmospheric Chemistry, CODATA Task Group on Chemical Kinetics, J. Phys. Chem. Ref. Data, 9, 295–471, 1980. Baulch, D. L., Cox, R. A., Crutzen, P. J., Hampson, Jr., R. F., Kerr, J. A., Troe, J., and Watson, R. T.: Evaluated Kinetic and Photo- References chemical Data for Atmospheric Chemistry: Supplement I, CO- DATA Task Group on Chemical Kinetics, J. Phys. Chem. Ref. Astholz, D. C., Brouwer, L., and Troe, J.: High-Temperature Data, 11, 327–496, 1982. Ultraviolet-Absorption Spectra of Polyatomic Molecules in Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, J. A., Troe, Shock Waves, Ber. Bunsenges. Phys. Chem., 85, 559–564, 1981. J., and Watson, R. T.: Evaluated Kinetic and Photochemical Atkinson, R., Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, J. Data for Atmospheric Chemistry: Supplement II, CODATA Task A., and Troe, J.: Evaluated Kinetic and Photochemical Data for Group on Gas Phase Chemical Kinetics, J. Phys. Chem. Ref. Atmospheric Chemistry: Supplement III, IUPAC Subcommittee Data, 13, 1259–1380, 1984. on Gas Kinetic Data Evaluation for Atmospheric Chemistry, J. Cobos, C. J. and Troe, J.: Prediction of Reduced Falloff Curves for Phys. Chem. Ref. Data, 18, 881–1097, 1989. Recombination Reactions at Low Temperatures, Z. Phys. Chem., Atkinson, R., Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, J. 217, 1–14, 2003. A., and Troe, J.: Evaluated Kinetic and Photochemical Data for Luther, K., Oum, K. and Troe, J.: The Role of the Radical-Complex Atmospheric Chemistry: Supplement IV, IUPAC Subcommittee Mechanism in the Ozone Recombination/Dissociation Reaction, on Gas Kinetic Data Evaluation for Atmospheric Chemistry, J. Phys. Chem. Chem. Phys., 7, 2764-2770, 2005. Phys. Chem. Ref. Data, 21, 1125–1568, 1992. Sander, S. P., Friedl, R. R., Golden, D. M., Kurylo, M. J., Huie, Atkinson, R., Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, R. E., Orkin, V. L., Moortgat, G. K., Ravishankara, A. R., Kolb, J. A., Rossi, M., and Troe, J.: Evaluated Kinetic, Photochemical, C. E., Molina, M. J., and Finlayson-Pitts, B. J.: Chemical Ki- and Heterogeneous Data for Atmospheric Chemistry: Supple- netics and Photochemical Data for Use in Atmospheric Studies. ment V, IUPAC Subcommittee on Gas Kinetic Data Evaluation NASA Panel for Data Evaluation, Evaluation Number 14., JPL for Atmospheric Chemistry, J. Phys. Chem. Ref. Data, 26, 521– Publication 02-25, 2003. 1011, 1997a. Oum, K., Sekiguchi, K., Luther, K., and Troe, J.: Observation of Atkinson, R., Baulch, D. L., Cox, R. A., Hampson, Jr., R. F., Kerr, J. Unique Pressure Effects in the Combination Reaction of Benzyl A., Rossi, M. J., and Troe, J.: Evaluated Kinetic and Photochem- Radicals in the Gas to Liquid Transition Region, Phys. Chem. ical Data for Atmospheric Chemistry: Supplement VI, IUPAC Chem. Phys., 5, 2931–2933, 2003. Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Troe, J.: Predictive Possibilities of Unimolecular Rate Theory, J. Chemistry, J. Phys. Chem. Ref. Data, 26, 1329–1499, 1997b. Phys. Chem., 83, 114–126, 1979. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4154 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry DATASHEETS Appendix 1: FO Reactions IV.A1.1 1 3 O( D) + COF → O( P) + COF (1) 2 2 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 (7.4± 1.2)× 10 298 Wine and Ravishankara, 1983 PLP-RF Branching Ratios k /k = 0.7± 0.07 298 Wine and Ravishankara, 1983 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + COF relative to that for O( D) + N . 2 2 Preferred Values −11 3 −1 −1 k = 7.4× 10 cm molecule s at 298 K. k /k = 0.7 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred value of k is based on the result of Wine and Ravishankara (1983). This study is much more direct than earlier studies. In that paper the authors state that the only chemical reaction involving COF which might be important in the stratosphere is the reaction O( D) + COF → F + CO and that this reaction would have to proceed by a complex mechanism 2 2 2 involving an intermediate adduct. References Wine, P. H. and Ravishankara, A. R.: Chem. Phys. Lett., 96, 129, 1983. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4155 IV.A1.2 1 3 O( D) + CH F → O( P) + CH F (1) 3 3 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (1.38± 0.06)× 10 298 Force and Wiesenfeld, 1981 PLP-RA −10 (1.65± 0.15)× 10 298 Schmoltner et al., 1993 PLP-RF Branching Ratios k /k = 0.25± 0.03 298 Force and Wiesenfeld, 1981 PLP-RA (a) k /k = 0.11± 0.05 298 Schmoltner et al., 1993 PLP-RF (b) k /k = 0.19± 0.05 298 Takahashi et al., 1996 PLP-LIF (b) Comments 1 3 (a) O( D) atoms were monitored by resonance absorption at 130.4 nm and compared to O( P) atoms in the presence of ozone 3 1 in He diluent where the O( P) atom yield from the O( D) + O reaction is 1.0. 3 1 1 (b) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CH F relative to that for O( D) + N . 3 2 Preferred Values −10 3 −1 −1 k = 1.5× 10 cm molecule s at 298 K. k /k = 0.18 at 298 K. Reliability 1 log k =± 0.15 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred value of k is the average of the values reported by Force and Wiesenfeld (1981) and by Schmoltner et al. (1993). The preferred value of the branching ratio k /k is the average of the values reported by Force and Wiesenfeld (1981), Schmoltner et al. (1993) and Takahashi et al. (1996). In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CH F was obtained. Burks and Lin (1981) have observed the appearance of stimulated emissions from vibrationally excited HF. Park and Wiesenfeld (1991) observed some production of HO, but they reported that HF elimination dominates over HO production. References Burks, T. L. and Lin, M. C.: Int. J. Chem. Kinet., 13, 977, 1981. Force, A. P. and Wiesenfeld, J. R.: J. Phys. Chem., 85, 782, 1981. Park, R. P. and Wiesenfeld, J. R.: Chem. Phys. Lett., 186, 170, 1991. Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem., 97, 8976, 1993. Takahashi, K., Wada, R., Matsumi, Y. and Kawasaki, M.: J. Phys. Chem., 100, 10145, 1996. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4156 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.3 1 3 O( D) + CH F → O( P) + CH F (1) 2 2 2 2 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 (5.13± 0.33)× 10 298 Schmoltner et al., 1993 PLP-RF Branching Ratios k /k = 0.70± 0.11 298 Schmoltner et al., 1993 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CH F relative to that for O( D) + N . 2 2 2 Preferred Values −11 3 −1 −1 k = 5.1× 10 cm molecule s at 298 K. k /k = 0.70 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.2 at 298 K. Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Schmoltner et al. (1993). In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CH F was obtained. Burks and Lin (1981) have observed the appearance of stimulated emissions from 2 2 vibrationally excited HF. References Burks, T. L. and Lin, M. C.: Int. J. Chem. Kinet., 13, 977, 1981. Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem., 97, 8976, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4157 IV.A1.4 1 3 O( D) + CHF → O( P) + CHF (1) 3 3 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (8.4± 0.8)× 10 298 Force and Wiesenfeld, 1981 PLP-RA −12 (9.76± 0.60)× 10 298 Schmoltner et al., 1993 PLP-RF Branching Ratios k /k = 0.77± 0.15 298 Force and Wiesenfeld, 1981 PLP-RA (a) k /k = 1.02± 0.15 298 Schmoltner et al., 1993 PLP-RF (b) Comments 1 3 (a) O( D) atoms were monitored by resonance absorption at 130.4 nm and compared to O( P) atoms in the presence of ozone 3 1 in He diluent where the O( P) atom yield from the O( D) + O reaction is 1.0. 3 1 1 (b) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CHF relative to that for O( D) + N . 3 2 Preferred Values −12 3 −1 −1 k = 9.1× 10 cm molecule s at 298 K. k /k = 0.9 at 298 K. Reliability 1 log k =± 0.15 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred value of k is the average of the values reported by Force and Wiesenfeld (1981) and Schmoltner et al. (1993). The preferred value of the branching ratio k /k is the average of the values reported by Force and Wiesenfeld (1981) and Schmoltner et al. (1993). In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CHF was obtained. Burks and Lin (1981) and Aker et al. (1987) have observed the appearance of stimulated emissions from vibrationally excited HF. References Aker, P. M., Niefer, B. I., Sloan, J. J. and Heydtmann, H.: J. Chem. Phys., 87, 203, 1987. Burks, T. L. and Lin, M. C.: Int. J. Chem. Kinet., 13, 977, 1981. Force, A. P. and Wiesenfeld, J. R.: J. Phys. Chem., 85, 782, 1981. Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem., 97, 8976, 1993 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4158 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.5 1 3 O( D) + CH CH F → O( P) + CH CH F (1) 3 2 3 2 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (2.61± 0.40)× 10 298 Schmoltner et al., 1993 PLP-RF Branching Ratios k /k = 0.18± 0.05 298 Schmoltner et al., 1993 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CH CH F relative to that for O( D) + N . 3 2 2 Preferred Values −10 3 −1 −1 k = 2.6× 10 cm molecule s at 298 K. k /k = 0.18 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred value of k and the branching ratio k /k are based on the results of Schmoltner et al. (1993), the only published study of this reaction. In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CH CH F was obtained. 3 2 References Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem., 97, 8976, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4159 IV.A1.6 1 3 O( D) + CH CHF → O( P) + CH CHF (1) 3 2 3 2 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (2.02± 0.15)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios k /k = 0.54± 0.07 298 Warren et al., 1991 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CH CHF relative to that for O( D) + N . 3 2 2 Preferred Values −10 3 −1 −1 k = 2.0× 10 cm molecule s at 298 K. k /k = 0.54 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Warren et al. (1991), the only published study of this reaction. In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CH CHF was obtained. 3 2 References Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett., 183, 403, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4160 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.7 1 3 O( D) + CH CF → O( P) + CH CF (1) 3 3 3 3 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −11 k = (5.8± 2.0)× 10 297 Green and Wayne, 1976 RR (a) Comments (a) O( D) produced by photolysis of NO at 229 nm. 1(CH CF )/1(N O) monitored by IR absorption spectroscopy. Mea- 2 3 3 2 1 1 sured rate coefﬁcient ratio of k /k(O( D) + N O) = 0.5 ± 0.1 is placed on an absolute basis by use of k(O( D) + N O) 2 2 2 −10 3 −1 −1 = 1.16 × 10 cm molecule s (IUPAC, current evaluation). The cited rate coefﬁcient refers to chemical reaction only and does not include physical quenching. Preferred Values −11 3 −1 −1 k = 5.8× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.5 Comments on Preferred Values The preferred value of k is derived from the relative rate results reported by Green and Wayne (1976) in the only published study of this reaction. It should be noted that this rate coefﬁcient refers to chemical reaction only and does not include physical quenching of O( D). References Green, R. G. and Wayne, R. P.: J. Photochem. 6, 371, 1976. IUPAC, http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4161 IV.A1.8 1 3 O( D) + CH FCF → O( P) + CH FCF (1) 2 3 2 3 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 (4.85± 0.25)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios +0.06 k /k = 0.94 298 Warren et al., 1991 PLP-RF (a) −0.10 Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CH FCF relative to that for O( D) + N . 2 3 2 Preferred Values −11 3 −1 −1 k = 4.9× 10 cm molecule s at 298 K. k /k = 0.94 at 298 K. Reliability 1 log k =± 0.3 at 298 K. +0.06 1 (k /k) = ( ) at 298 K. −0.10 Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Warren et al. (1991), the only published study of this reaction. In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CH FCF was obtained. 2 3 References Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett., 183, 403, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4162 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.9 1 3 O( D) + CHF CF → O( P) + CHF CF (1) 2 3 2 3 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (1.23± 0.06)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios +0.15 k /k = 0.85 298 Warren et al., 1991 PLP-RF (a) −0.22 Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CHF CF relative to that for O( D) + N . 2 3 2 Preferred Values −10 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. k /k = 0.85 at 298 K. Reliability 1 log k =± 0.3 at 298 K. +0.15 1 (k /k) = ( ) at 298 K. −0.3 Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Warren et al. (1991). In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CHF CF was obtained. 2 3 References Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett., 183, 403, 1991. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4163 IV.A1.10 HO + CH F → H O + CH F 3 2 2 ◦ −1 1H = -78.2 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (1.60± 0.35)× 10 296 Howard and Evenson, 1976 DF-LMR −14 (2.18± 0.18)× 10 297 Nip et al., 1979 FP-RA −12 8.11× 10 exp[-(1887± 61)/T ] 292-480 Jeong et al., 1984 DF-RF (a) −14 (1.40± 0.09)× 10 292 −14 (1.71± 0.24)× 10 298 Bera and Hanrahan, 1988 PR-A −12 1.75× 10 exp[-(1300± 100)/T ] 243-373 Schmoltner et al., 1993 PLP/FP-LIF −14 (2.09± 0.08)× 10 298 Relative Rate Coefﬁcients −14 (1.71± 0.08)× 10 296± 2 Wallington and Hurley, 1993 RR (b) −14 (1.41± 0.07)× 10 296± 2 Wallington and Hurley, 1993 RR (c) −14 (1.32± 0.12)× 10 295 Møgelberg et al., 1994 RR (d) −18 2 2.77× 10 T exp[-(754± 34)/T ] 298-363 Hsu and DeMore, 1995 RR (e) −14 1.96× 10 298 −18 2 4.21× 10 T exp[-(856± 82)/T ] 308-393 DeMore, 1996 RR (f) Comments (a) The rate expression cited in Jeong et al. (1984) supersedes that reported in Jeong and Kaufman (1982). Jeong et al. (1984) also corrects an erroneously reported rate measurement at 480 K. (b) HO radicals were generated by photolysis of CH ONO at 933 mbar total pressure of air. The decay of CH F was inferred 3 3 from the measured formation of HC(O)F, using a formation yield of HC(O)F of 0.90 as measured in separate Cl -CH F- 2 3 NO-air irradiations. The concentrations of HC(O)F and acetylene were measured by FTIR absorption spectroscopy. The measured rate coefﬁcient ratio of k(HO + CH F)/k(HO + C H ) = 0.0201 ± 0.0009 was placed on an absolute basis by 3 2 2 −13 3 −1 −1 using k(HO + C H ) = 8.49× 10 cm molecule s at 296 K and 1013 mbar air (Sørensen et al. 2003). 2 2 (c) HO radicals generated by the photolysis of O at 254 nm in the presence of H . The concentrations of CH and CH F 3 2 4 3 were measured by FTIR absorption spectroscopy. The measured rate coefﬁcient ratio of k(HO + CH F)/k(HO + CH ) 3 4 −15 3 −1 −1 = 2.30 ± 0.11 was placed on an absolute basis by using k(HO + CH ) = 6.14 × 10 cm molecule s at 296 K (IUPAC, current recommendation). (d) HO radicals generated by the photolysis of O at 254 nm in the presence of H . The decay of CH and CH F concen- 3 2 4 3 trations was monitored by FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CH F)/k(HO + CH ) = 2.2 3 4 −15 3 −1 −1 ± 0.2 was placed on an absolute basis by using k(HO + CH ) = 6.01 × 10 cm molecule s at 295 K (IUPAC, current recommendation). (e) HO radicals were generated by the photolysis of H O at 185 nm or of O -H O mixtures in the UV in H O (or O -H O)- 2 3 2 2 3 2 CH F-CH CHF -O -N mixtures. The concentrations of CH F and CH CHF were measured by IR spectroscopy. The 3 3 2 2 2 3 3 2 measured rate coefﬁcient ratio of k(HO + CH F)/k(HO + CH CHF ) = (0.99 ± 0.10) exp[-(174 ± 34)/T ] is placed on 3 3 2 −18 2 3 −1 −1 an absolute basis by using a rate coefﬁcient of k(HO + CH CHF ) = 2.80× 10 T exp(-580/T ) cm molecule s 3 2 (IUPAC, current recommendation). (f) HO radicals generated by the photolysis of O at 254 nm in the presence of H O vapour. The decay of CH Cl and CH F 3 2 3 3 concentrations was monitored by FTIR spectroscopy. The rate coefﬁcient ratio of k(HO + CH F)/k(HO + CH Cl) = (0.97 3 3 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4164 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry ± 0.23) exp[-(156 ± 82)/T ] was measured over the temperature range 308-393 K. The rate coefﬁcient ratio was placed −18 2 3 −1 −1 on an absolute basis by using k(HO + CH Cl) = 4.34 × 10 T exp(-700/T ) cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 2.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.9 x 10 exp(-1350/T ) cm molecule s over the temperature range 240-300 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The absolute rate coefﬁcients of Schmoltner et al. (1993) are higher than those reported previously by Jeong and Kaufman (1982) and Jeong et al. (1984), although the discrepancy decreases with increasing temperature. The absolute rate coefﬁcients of Schmoltner et al. (1993), although exhibiting scatter at temperatures≤ 273 K, are in good agreement with the relative rate coefﬁcients of Hsu and DeMore (1995) and DeMore (1996) at 298 K and above. The absolute rate coefﬁcient of Nip et al. (1979) is in good agreement with the data of Schmoltner et al. (1993), Hsu and DeMore (1995) and DeMore (1996). Because secondary reactions of HO radicals with CH F radicals and other radical species were expected to have occurred in the study of Bera and Hanrahan (1988), their rate coefﬁcient was consequently not used in the evaluation. The absolute rate coefﬁcients of Howard and Evenson (1976), Jeong and Kaufman (1982), Wallington and Hurley (1993), and Møgelberg et al. (1994) appear to be systematically lower than other studies, and therefore they were not used in the evaluation. The data of Nip et al. (1979), Schmoltner et al. (1993), Hsu and DeMore (1995) and DeMore (1996) were ﬁtted to the 2 −18 2 3 −1 −1 three-parameter equation k = CT exp(-D/T ), resulting in k = 3.66 × 10 T exp(-818/T ) cm molecule s over the temperature range 243-393 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, 2 2 T , of 265 K and is derived from the three parameter equation with A = C e T and B = D+ 2T . m m References Bera, R. K. and Hanrahan, R. J.: Radiat. Phys. Chem. 32, 579, 1988. DeMore, W. B.: J. Phys. Chem. 100, 5813, 1996. Howard, C. J. and Evenson, K. M.: J. Chem. Phys. 64, 197, 1976. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem. 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem. 88, 1222, 1984. Møgelberg, T. E., Nielsen, O. J., Sehested, J., Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett. 226, 171, 1994. Nip, W. S., Singleton, D. L., Overend, R. and Paraskevopoulos, G.: J. Phys. Chem. 83, 2440, 1979. Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 97, 8976, 1993. Sørensen, M., Kaiser, E. W., Hurley, M. D., Wallington, T. J. and Nielsen, O. J.: Int. J. Chem. Kinet. 35, 191, 2003. Wallington, T. J. and Hurley, M. D.: Environ. Sci. Technol. 27, 1448, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4165 IV.A1.11 HO + CH F → H O + CHF 2 2 2 2 ◦ −1 1H = -65.0 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 (7.8± 1.2)× 10 296 Howard and Evenson, 1976 DF-LMR −12 7.42× 10 exp[-(2100± 200)/T ] 293-429 Clyne and Holt, 1979 DF-RF −15 (5.8± 0.3)× 10 293 −14 (1.17± 0.14)× 10 297 Nip et al., 1979 FP-RA −12 4.4× 10 exp[-(1766± 50)/T ] 250-492 Jeong et al., 1984 DF-RF (a) −14 (1.12± 0.075)× 10 298 −15 (8.8± 1.4)× 10 298 Bera and Hanrahan, 1988 PR-A −12 1.57× 10 exp[-(1470± 100)/T ] 222-381 Talukdar et al., 1991 FP-LIF −14 (1.13± 0.01)× 10 298 −15 (2.52± 0.25)× 10 223 Schmoltner et al., 1993 PLP/FP-LIF −14 (1.09± 0.03)× 10 298 −14 (1.00± 0.03)× 10 298 Szilagyi et al., 2000 DF-RF Relative Rate Coefﬁcients −18 2 2.24× 10 T exp[-(857± 24)/T ] 297-383 Hsu and DeMore, 1995 RR (b) −14 1.12× 10 297 Comments (a) The rate expression cited in Jeong et al. (1984) supersedes that reported in Jeong and Kaufman (1982). (b) Relative rate method. HO radicals were generated from the photolysis of H O at 185 nm or of O -H O mixtures in the UV 2 3 2 in H O (or O -H O)-CH F -CH CHF -O -N mixtures. The concentrations of CH F and CH CHF were measured by 2 3 2 2 2 3 2 2 2 2 2 3 2 FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CH F )/k(HO + CH CHF ) = (0.80± 0.06) exp[-(277 2 2 3 2 −18 2 ± 24)/T ] is placed on an absolute basis using a rate coefﬁcient of k(HO + CH CHF ) = 2.80 × 10 T exp(-580/T ) 3 2 3 −1 −1 cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 1.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.3× 10 exp(-1590/T ) cm molecule s over the temperature range 220-300 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The absolute rate coefﬁcients of Schmoltner et al. (1993) at 223 K and 298 K are in excellent agreement with the earlier and much more extensive rate coefﬁcient data of Talukdar et al. (1991). The room temperature rate coefﬁcients of Nip et al. (1983), Jeong and Kaufman (1982), Jeong et al. (1984), Talukdar et al. (1991) and Schmoltner et al. (1993) are in good agreement, but www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4166 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry are∼ 30% higher than those of Howard and Evenson (1976), Clyne and Holt (1979) and Bera and Hanrahan (1988). The data of Clyne and Holt (1979) are not considered reliable and that of Bera and Hanrahan (1988) may have been subject to secondary reactions. The rate coefﬁcients measured by Jeong and Kaufman (1982) (250–492 K) and Talukdar et al. (1991) (222–381 K) are in good agreement over the temperature range where they overlap. The rate coefﬁcient data of Nip et al. (1983), Jeong and Kaufman (1982), Talukdar et al. (1991), Hsu and DeMore (1995), Schmoltner et al. (1993), and Szilagyi et al. (2000) have been ﬁtted to the three parameter equation k = CT exp(−D/T ), −18 2 3 −1 −1 resulting in k = 4.80 × 10 T exp(-1080/T ) cm molecule s over the temperature range 222–492 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 255 K and is derived from the three 2 2 parameter equation with A = C e T and B = D+ 2T . References Bera, R. K. and Hanrahan, R. J.: Radiat. Phys. Chem. 32, 579, 1988. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Howard, C. J. and Evenson, K. M.: J. Chem. Phys. 64, 197, 1976. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem. 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem. 88, 1222, 1984. Nip, W. S., Singleton, D. L., Overend, R. and Paraskevopoulos, G.: J. Phys. Chem. 83, 2440, 1979. Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 97, 8976, 1993. Szilagyi, I., Dobe, S. and Berces, T.: React. Kinet. Catal. Lett. 70, 319, 2000. Talukdar, R., Mellouki, A., Gierczak, T., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 95, 5815, Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4167 IV.A1.12 HO + CHF → H O + CF 3 2 3 ◦ −1 1H = -47.5 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −16 (2.0± 0.2)× 10 296 Howard and Evenson, 1976 DF-LMR −15 (1.3± 0.4)× 10 296 Clyne and Holt, 1979 DF-RF −15 (1.4± 0.6)× 10 430 −16 (3.49± 1.66)× 10 297 Nip et al., 1979 FP-RA −12 2.98× 10 exp[-(2908± 156)/T ] 387-480 Jeong et al., 1984 DF-RF (a) −16 1.71× 10 298 (b) −15 (2.3± 0.4)× 10 298 Bera and Hanrahan, 1988 PR-RA −13 6.93× 10 exp[-(2300± 100)/T ] 252-374 Schmoltner et al., 1993 FP-LIF −16 (3.08± 0.28)× 10 298 −12 1.1× 10 exp[-(2300± 207)/T ] 298-753 Medhurst et al., 1997 PLP-LIF −16 (1.5± 0.2)× 10 298 Relative Rate Coefﬁcients −18 2 1.05× 10 T exp[-(1774± 44)/T ] 298-383 Hsu and DeMore, 1995 RR (c) −16 2.42× 10 298 −19 2 6.19× 10 T exp[-(1523± 34)/T ] 253-343 Chen et al., 2003 RR (d,e) −16 3.32× 10 298 −18 2 1.12× 10 T exp[-(1706± 44)/T ] 253-343 Chen et al., 2003 RR (d,f) −16 3.25× 10 298 Comments (a) The rate expression cited in Jeong et al. (1984) supersedes that reported in Jeong and Kaufman (1982). Jeong et al. (1984) also corrects an erroneously reported rate measurement at 465 K. (b) Extrapolated value. (c) Relative rate method. HO radicals were generated from the photolysis of H O at 185 nm or of O -H O mixtures in the UV 2 3 2 in H O (or H O-O )-CHF -CHF CF -N -O mixtures. The concentrations of CHF and CHF CF were measured by 2 2 3 3 2 3 2 2 3 2 3 FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHF )/k(HO + CHF CF ) = (1.14± 0.08) exp[-(654 3 2 3 −19 2 ± 44)/T ] is placed on an absolute basis by using a rate coefﬁcient of k(HO + CHF CF ) = 9.24× 10 T exp(-1120/T ) 2 3 3 −1 −1 cm molecule s (IUPAC, current recommendation). (d) Relative rate method. HO radicals were generated from the photolysis of H O at 254 nm in the presence of a continuous ﬂow of a 3% O in O mixture. The concentrations of CHF and reference compounds were measured by GC-FID. Total 3 2 3 initial reactor pressure was 266 mbar (200 Torr) with the pressure rising to 400–666 mbar (300–500 Torr) at the end of an experiment. (e) Relative to CHF CF . An Arrhenius plot of the Chen et al. (2003) data gives a rate coefﬁcient ratio of k(HO + 2 3 CHF )/k(HO + CHF CF ) = (0.67 ± 0.12) exp[-(403 ± 34)/T ] over the temperature range 253–343 K. The rate co- 3 2 3 −19 2 efﬁcient ratio was placed on an absolute basis by using a rate coefﬁcient of k(HO + CF CHF ) = 9.24 × 10 T 3 2 3 −1 −1 exp(-1120/T ) cm molecule s (IUPAC, current recommendation). (f) Relative to CHF Cl. An Arrhenius plot of the Chen et al. (2003) data gives a rate coefﬁcient ratio of k(HO + CHF )/k(HO 2 3 + CHF Cl) = (0.74 ± 0.17) exp[-(706 ± 44)/T ] over the temperature range 253–343 K. The rate coefﬁcient ratio was www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4168 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry −18 2 3 placed on an absolute basis by using a rate coefﬁcient of k(HO + CHF Cl) = 1.52 × 10 T exp(-1000/T ) cm −1 −1 molecule s (IUPAC, current recommendation). Preferred Values −16 3 −1 −1 k = 2.7× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 6.9× 10 exp(-2340/T ) cm molecule s over the temperature range 250-300 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The absolute rate coefﬁcient study of Schmoltner et al. (1993) and the relative rate studies of Chen et al. (2003) are the only temperature-dependent studies carried out at temperatures below 298 K. The rate coefﬁcients of Schmoltner et al. (1993) and Chen et al. (2003) are in very good agreement over the temperature range 252–343 K. The rate coefﬁcients from the relative rate study of Hsu and DeMore (1995) are ∼ 10-20% lower than the absolute rate coefﬁcients of Schmoltner et al. (1993) and the relative rate studies of Chen et al. (2003) over the temperature range common to all studies, with the disagreement increasing with decreasing temperature. However, the absolute rate coefﬁcients of Jeong and Kaufmann (1982) are in good agreement with the relative rate coefﬁcients of Hsu and DeMore (1995) at temperatures 383–387 K. The data of Medhurst et al. (1997) were obtained at temperatures predominantly above room temperature. Moreover, the rate coefﬁcients calculated from the Arrhenius ﬁt to their experimental data are substantially higher than any other study. Therefore, the data of Medhurst et al. (1997) were not used in the evaluation. The rate coefﬁcient of Nip et al. (1979) is in good agreement with the data of Schmoltner et al. (1993) and Chen et al. (2003), but the rate coefﬁcient of Howard and Evenson (1976) is∼ 40% lower. The data of Clyne and Holt (1979) and Bera and Hanrahan (1988) were not used due to their inconsistency with the other data. The absolute rate coefﬁcients of Howard and Evenson (1976), Nip et al. (1979), Jeong and Kaufman (1982), Schmoltner et al. (1993) and the relative rate coefﬁcients of Chen et al. (2003) have been ﬁtted to the three parameter equation k = CT −18 2 3 −1 −1 exp(-D/T ), resulting in k = 1.42× 10 T exp(-1798/T ) cm molecule s over the temperature range 252–480 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 270 K and is derived from 2 2 the three parameter equation with A = C e T and B = D+ 2T . The relative rate data of Hsu and DeMore (1995) are∼ 10% lower than the preferred values. References Bera, R. K. and Hanrahan, R. J.: Radiat. Phys. Chem. 32, 579, 1988. Chen, L., Kutsuna, S., Tokuhashi, K. and Sekiya, A.: Int. J. Chem. Kinet. 35, 317, 2003. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Howard, C. J. and Evenson, K. M.: J. Chem. Phys. 64, 197, 1976. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem. 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem. 88, 1222, 1984. Medhurst, L. J., Fleming, J. and Nelson, H. H.: Chem. Phys. Lett. 266, 607, 1997. Nip, W. S., Singleton, D. L., Overend, R. and Paraskevopoulos, G.: J. Phys. Chem. 83, 2440, 1979. Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 97, 8976, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4169 IV.A1.13 HO + CF → HOF + CF 4 3 ◦ −1 1H = 327.2 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −16 <4× 10 296± 2 Howard and Evenson, 1976 DF-LMR −15 <1× 10 293 Clyne and Holt, 1979 DF-RF −18 <2× 10 ∼298 Ravishankara et al., 1993 PLP-LIF (a) Comments (a) Not explicitly reported, but expected to be a pulsed photolysis system with LIF detection of HO radicals as carried out by Schmoltner et al. (1993) for HO radical reaction rate coefﬁcient measurements with related hydroﬂuorocarbons. Preferred Values −18 3 −1 −1 k < 2× 10 cm molecule s at 298 K. Comments on Preferred Values The preferred value is the upper limit to the rate coefﬁcient reported by Ravishankara et al. (1993). References Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Howard, C. J. and Evenson, K. M.: J. Chem. Phys. 64, 197, 1976. Ravishankara, A. R., Solomon, S., Turnipseed, A. A. and Warren, R. F.: Science 259, 194, 1993. Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 97, 8976, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4170 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.14 HO + CH CH F → H O + CH CHF (1) 3 2 2 3 → H O + CH CH F (2) 2 2 2 ◦ −1 1H (1) = -74.4 kJ·mol ◦ −1 1H (2) = -59.6 kJ·mol Rate coefﬁcient data(k =k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (2.32± 0.37)× 10 297± 2 Nip et al., 1979 FP-RA −12 2.69× 10 exp[-(750± 100)/T ] 243-373 Schmoltner et al., 1993 PLP/FP-LIF −13 (2.17± 0.29)× 10 298 −12 6.78× 10 exp[-(1033± 74)/T ] 298-480 Kozlov et al., 2003 FP-RF −12 2.42× 10 exp[-(716± 36)/T ] 210-298 −13 (2.20± 0.03)× 10 298 Relative Rate Coefﬁcients −17 2 1.73× 10 T exp[-(657± 36)/T ] 285-364 Hsu and DeMore, 1995 RR (a) −13 1.69× 10 298 Comments (a) HO radicals were generated by the photolysis of H O at 185 nm or of H O-O mixtures in the UV in H O (or H O-O )- 2 2 3 2 2 3 CH CH F-C H -O -N mixtures. The concentrations of CH CH F and C H were measured by FTIR spectroscopy. The 3 2 2 6 2 2 3 2 2 6 measured rate coefﬁcient ratio of k(HO + CH CH F)/k(HO + C H ) = (1.16± 0.13) exp[-(158± 36)/T ] is placed on an 3 2 2 6 −17 2 3 −1 −1 absolute basis using a rate coefﬁcient of k(HO + C H ) = 1.49 × 10 T exp(-499/T ) cm molecule s (IUPAC, 2 6 current recommendation). Preferred Values −13 3 −1 −1 k = 2.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.7× 10 exp(-765/T ) cm molecule s over the temperature range 210-300 K. k /k = 0.85 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. k /k =± 0.15 at 298 K. Comments on Preferred Values The rate coefﬁcients of Nip et al. (1979), Schmoltner et al. (1993) and Kozlov et al. (2003) are in good agreement over the temperature range 243-373 K. The relative rate coefﬁcients of Hsu and DeMore (1995) display a higher temperature dependence compared to that observed by Schmoltner et al. (1993) and Kozlov et al. (2003). At room temperature, the rate coefﬁcients of Hsu and DeMore (1995) are∼35% lower than those of Nip et al. (1979), Schmoltner et al. (1993) and Kozlov et al. (2003). The source of the disagreement is not known although impurities in the reactant were ruled out in the Kozlov et al. (2003) study. Above 298 K (329–364 K), the agreement between the data of Hsu and DeMore (1995), Schmoltner et al. (1993) and Kozlov et al. (2003) is better. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4171 The study by Kozlov et al. (2003) shows curvature in the Arrhenius plot. Singleton et al. (1980) determined that 85% of the abstraction by HO is from the CH F group at 298 K. Therefore, at least some of the observed curvature is probably due to the increasing importance of H atom abstraction from the unsubstituted methyl group (CH ) with increasing temperature. The absolute rate coefﬁcients of Nip et al. (1979), Schmoltner et al. (1993) and Kozlov et al. (2003) were ﬁtted to the 2 −18 2 3 −1 −1 three-parameter equation k = CT exp(-D/T ), resulting in k = 6.12 × 10 T exp(-275/T ) cm molecule s over the temperature range 210–480 K. The preferred Arrhenius expression k = A exp(-B/T ), is centered on a mid-range temperature, 2 2 T , of 245 K and is derived from the three parameter equation with A = C e T and B = D+ 2T . The relative rate data of m m Hsu and DeMore (1995) are approximately 20-30% lower than the preferred value at 298 K. References Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Kozlov, S. N., Orkin, V. L. and Kurylo, M. J.: J. Phys. Chem. A. 107, 2239, 2003. Nip, W. S., Singleton, D. L., Overend, R. and Paraskevopoulos, G.: J. Phys. Chem. 83, 2440, 1979. Schmoltner, A. M., Talukdar, R. K., Warren, R. F., Mellouki, A., Goldfarb, L., Gierczak, T., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 97, 8976, 1993. Singleton, D. L., Paraskevopoulos, G. and Irwin, R. S.: J. Phys. Chem. 84, 2339, 1980. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4172 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.15 HO + CH CHF → H O + CH CHF (1) 3 2 2 2 2 → H O + CH CF (2) 2 3 2 ◦ −1 1H (1) = -53.8 kJ·mol ◦ −1 1H (2) = -69.8 kJ·mol Rate coefﬁcient data(k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (3.12± 0.70)× 10 296 Howard and Evenson, 1976 DF-LMR −14 (3.50± 0.50)× 10 293 Handwerk and Zellner, 1978 FP-RA −12 2.92× 10 exp[-(1200± 100)/T ] 293-417 Clyne and Holt, 1979 DF-RF −14 (4.66± 0.16)× 10 293 −14 (3.7± 0.4)× 10 297± 2 Nip et al., 1979 FP-RA −12 1.42× 10 exp[-(1050)/T ] 220-423 Brown et al. 1990 DF-RF −14 4.2× 10 298 −13 9.6× 10 exp[-(940± 130)/T ] 270-400 Liu et al., 1990 FP-RF −14 (4.22± 0.45)× 10 298 −12 1.0× 10 exp[-(980± 50)/T ] 212-349 Gierczak et al., 1991 DF-LMR/FP-LIF −14 (3.76± 0.6)× 10 293 −12 3.9× 10 exp[-(1370± 260)/T ] 295-388 Nielsen, 1991 PR-RA −14 (4.7± 1.1)× 10 295 −12 3.24× 10 exp[-(1372± 89)/T ] 298-480 Kozlov et al., 2003 FP-RF −13 9.36× 10 exp[-(998± 56)/T ] 210-298 −14 (3.38± 0.05)× 10 298 Relative Rate Coefﬁcients −14 (3.86± 0.67)× 10 298± 2 DeMore, 1992 RR (a) −14 (3.45± 0.34)× 10 298± 2 DeMore, 1992 RR (b) −18 2 3.44× 10 T exp[-(690± 57)/T ] 298-358 Hsu and DeMore, 1995 RR (c) −14 3.02× 10 298 −20 2.82 1.18× 10 T exp[-(388± 67)/T ] 298-358 Hsu and DeMore, 1995 RR (b) −14 3.05× 10 298 −18 2 2.53× 10 T exp[-(557± 19)/T ] 286-403 Wilson et al., 2003 RR (d,e) −14 3.47× 10 298 −18 2 1.22× 10 T exp[-(329± 42)/T ] 290-391 Wilson et al., 2003 RR (d,f) −14 3.59× 10 298 −14 (3.12± 0.58)× 10 295± 2 Taketani et al., 2005 RR (g,h) −14 (3.03± 0.53)× 10 295± 2 Taketani et al., 2005 RR (g,i) Comments (a) HO radicals were generated by the photolysis of H O at 185 nm in H O-CH CHF -C H -N -O mixtures. The concen- 2 2 3 2 2 6 2 2 trations of CH CHF and C H were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + 3 2 2 6 CH CHF )/k(HO + C H ) = 0.161± 0.028 is placed on an absolute basis by use of a rate coefﬁcient of k(HO + C H ) = 3 2 2 6 2 6 −13 3 −1 −1 2.4× 10 cm molecule s (IUPAC, current recommendation). (b) HO radicals were generated by the photolysis of H O at 185 nm or of O -H O mixtures in H O (or O -H O)-CH CHF - 2 3 2 2 3 2 3 2 CH -N -O mixtures. The concentrations of CH CHF and CH were measured by FTIR spectroscopy. The measured 4 2 2 3 2 4 rate coefﬁcient ratios of k(HO + CH CHF )/k(HO + CH ) = 5.2 ± 0.5 (DeMore, 1992) and k(HO + CH CHF )/k(HO 3 2 4 3 2 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4173 + CH ) = (0.64 ± 0.13) exp[(599 ± 67)/T ] (Hsu and DeMore, 1995) are placed on an absolute basis by use of a rate −20 2.82 3 −1 −1 coefﬁcient of k(HO + CH ) = 1.85× 10 T exp(-987/T ) cm molecule s (IUPAC, current recommendation). (c) HO radicals were generated by the photolysis of H O at 185 nm or of O -H O mixtures in the UV in H O (or H O- 2 3 2 2 2 O )-CH CHF -CH CCl -O -N mixtures. The concentrations of CH CHF and CH CCl were measured by FTIR 3 3 2 3 3 2 2 3 2 3 3 spectroscopy. The measured rate coefﬁcient ratio of k(HO + CH CHF )/k(HO + CH CCl ) = (1.53 ± 0.28) exp[(220 3 2 3 3 −18 2 ± 57)/T ] is placed on an absolute basis by use of a rate coefﬁcient of k(HO + CH CCl ) = 2.25× 10 T exp(-910/T ) 3 3 3 −1 −1 cm molecule s (IUPAC, current recommendation). (d) Relative rate method. HO radicals were generated by photolyzing H O vapor at 185 nm. Reactant and reference com- pound concentrations were monitored by GC/MS. (e) Relative to C H . An Arrhenius plot of the data gives the temperature dependence of the measured ratios as (0.17± 0.01) 2 6 −17 2 exp[-(58 ± 19)/T ], which is placed on an absolute basis using a rate coefﬁcient of k(HO + C H ) = 1.49 × 10 T 2 6 3 −1 −1 exp(-499/T ) cm molecule s (IUPAC, current recommendation). (f) Relative to cyclopropane. An Arrhenius plot of the data gives the temperature dependence of the measured ratios as (0.29 ± 0.10) exp[(125± 42)/T ] ], which is placed on an absolute basis using a rate coefﬁcient of k(HO + cyclo-C H ) = 4.21 3 6 −18 2 3 −1 −1 × 10 T exp(-454/T ) cm molecule s (Atkinson, 2003). (g) Relative rate method. HO radicals were generated by the UV photolysis of CH ONO in the presence of the reactant in 700 Torr total pressure of air diluent. Reference compound concentrations were monitored by FTIR. CH CHF loss was 3 2 measured indirectly from the observed formation of COF . −3 (h) Relative to C H . The measured rate coefﬁcient ratio of k(CH CHF + HO)/k(C H + HO) = (3.59 ± 0.27) × 10 2 4 3 2 2 4 −12 3 −1 −1 placed on an absolute basis by using a rate coefﬁcient of k(C H + HO) = 8.7 × 10 cm molecule s at 295 K 2 4 (Calvert et al., 2000). −2 (i) Relative to C H . The measured rate coefﬁcient ratio of k(CH CHF + HO)/k(C H + HO) = (3.58 ± 0.12) × 10 is 2 2 3 2 2 2 −13 3 −1 −1 placed on an absolute basis by using a rate coefﬁcient of k(C H + HO) = 8.45 × 10 cm molecule s at 296 K 2 2 (Sørensen et al., 2003). Preferred Values −14 3 −1 −1 k = 3.6× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.25× 10 exp(-1070/T ) cm molecule s over the temperature range 210-300 K. Reliability +0.10 1 log k = at 298 K. −0.20 1 (E/R) = K. −400 Comments on Preferred Values The absolute rate coefﬁcients of Handwerk and Zellner (1978), Nip et al. (1979), Gierczak et al. (1991), and Kozlov et al. (2003) are in good agreement, and the relative rate coefﬁcients of DeMore (1992) and Wilson et al. (2003) agree well with these absolute rate coefﬁcients. The absolute rate coefﬁcients of Clyne and Holt (1979) and Nielsen (1991) are systematically higher than the other absolute or relative rate coefﬁcients, hence these data were not used in the evaluation. The data of Brown et al. (1990) are scattered and subject to large uncertainties, and those of Liu et al. (1990) exhibit a lower temperature dependence than the other absolute or relative rate coefﬁcients - these studies were also not used in the evaluation. It is possible that the studies of Clyne and Holt (1979), Brown et al. (1990), Liu et al. (1990) and Nielsen (1991) were affected by reactant impurities. Of the data of Wilson et al. (2003), the rate data relative to C H agrees very well with the absolute rate coefﬁcients 2 6 of Gierczak et al. (1991) and Kozlov et al. (2003). The Wilson et al. (2003) data relative to cyclopropane exhibits a lower temperature dependence compared with the data of Gierczak et al. (1991), Kozlov et al. (2003) and Wilson et al. (2003) relative to C H . This is attributed to uncertainties in the recommended rate constant for the cyclopropane reaction. Hence, 2 6 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4174 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry only the Wilson et al. (2003) data relative to C H were used in the evaluation. The relative rate coefﬁcients of DeMore (1992) 2 6 relative to C H and CH are in good agreement with each other, and in good agreement with the absolute rate coefﬁcients of 2 6 4 Howard and Evenson (1976), Handwerk and Zellner (1978), Nip et al. (1979), Gierczak et al. (1991), Kozlov et al. (2003), and the rate coefﬁcients of Wilson et al. (2003) relative to C H . The relative rate coefﬁcients of Hsu and DeMore (1995) are 2 6 systematically lower and exhibit a slightly higher temperature dependence than the data of Gierczak et al. (1991), Kozlov et al. (2003), and Wilson et al. (2003) relative to C H . 2 6 The rate coefﬁcient data of Howard and Evenson (1976), Handwerk and Zellner (1978), Nip et al. (1979), Gierczak et al. (1991) (using all data in the temperature range 212–422.5 K), DeMore (1992), Kozlov et al. (2003) and Wilson et al. (2003) 2 −18 2 (relative to C H ) were ﬁtted to a three parameter equation k = CT exp(-D/T ) giving k = 2.80 × 10 T exp(-580/T ) 2 6 over the temperature range 210–480 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range 2 2 temperature, T , of 245 K and is derived from the three parameter equation with A = C e T and B = D+ 2T . The relative m m rate data of Hsu and DeMore (1995) are approximately 16-18% lower than the preferred value at 298 K. References Atkinson, R.: Atmos. Chem. Phys. 3, 2233, 2003. Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ. 24A, 2499, 1990. Calvert, J. G., Atkinson, R., Kerr, J. A., Madronich, S., Moortgat, G. K., Wallington, T. J., and Yarwood, G.: The Mechanism of Atmospheric Oxidation of the Alkenes, Oxford University Press, New York, 2000. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. DeMore, W. B.: Optical Methods in Atmospheric Chemistry, Soc. Photo-Optic. Instrum. Eng. 1715, 72, 1992. Gierczak, T., Talukdar, R., Vaghjiani, G. L., Lovejoy, E. R. and Ravishankara, A. R.: J. Geophys. Res. 96, 5001, 1991. Handwerk V. and Zellner, R.: Ber. Bunsenges. Phys. Chem. 82, 1161, 1978. Howard, C. J. and Evenson, K. M.: J. Chem. Phys. 64, 4303, 1976. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Kozlov, S. N., Orkin, V. L. and Kurylo, M. J.: J. Phys. Chem. A. 107, 2239, 2003. Liu, R., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem. 94, 3247, 1990. Nielsen, O. J.: Chem. Phys. Lett. 187, 286, 1991. Nip, W. S., Singleton, D. L., Overend, R. and Paraskevopoulos, G.: J. Phys. Chem. 83, 2440, 1979. Sørensen, M., Kaiser, E. W., Hurley, M. D., Wallington, T. J. and Nielsen, O. J.: Int. J. Chem. Kinet. 35, 191, 2003. Taketani, F., Nakayama, T., Takahashi, K., Matsumi, Y., Hurley, M. D., Wallington, T. J., Toft, A., and Sulbaek Andersen, M. P.: J. Phys. Chem. A. 109, 9061, 2005. Wilson, E. W., Jr., Jacoby, A. M., Kukta, S. J., Gilbert, L. E. and DeMore, W. B.: J. Phys. Chem. A. 107, 9357, 2003. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4175 IV.A1.16 HO + CH CF → H O + CH CF 3 3 2 2 3 ◦ −1 1H = -47.4 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 (6.92± 1.20)× 10 exp [-(3200± 500)/T ] 333-425 Clyne and Holt, 1979 DF-RF (a) −15 < 1.0× 10 293 −15 (1.71± 0.43)× 10 298 Martin and Paraskevopoulos, 1983 FP-RA −12 2.12× 10 exp[-(2200± 200)/T ] 261-374 Talukdar et al., 1991 DF-LMR/FP-LIF (b) −15 (1.35± 0.25)× 10 298 −13 9.51× 10 exp[-(1979± 65)/T ] 298-370 Orkin et al., 1996 FP-RF −15 (1.24± 0.09)× 10 298 Relative Rate Coefﬁcients −21 2.82 7.96× 10 T exp[-(1210± 90)/T ] 298-403 Hsu and DeMore, 1995 RR (c,d) −15 1.30× 10 298 −18 2 2.00× 10 T exp[-(1490± 21)/T ] 298-383 Hsu and DeMore, 1995 RR (c,e) −15 1.20× 10 298 Comments (a) Although experiments were conducted over the temperature range 293–425 K, only an upper limit to the rate coefﬁcient was obtained at 293 K. (b) Kinetic data were obtained over the temperature range 223–374 K. Because the Arrhenius plot exhibited curvature below 261 K, the Arrhenius expression cited in the table was derived from the rate coefﬁcients between 261–374 K. (c) HO radicals generated by the photolysis of H O at 185 nm or of O -H O mixtures in the UV in H O (or O -H O)- 2 3 2 2 3 2 CH CF -CH (or CHF CF )-O -N mixtures. The concentrations of CH CF and CH (or CHF CF ) were measured by 3 3 4 2 3 2 2 3 3 4 2 3 FTIR spectroscopy. (d) The measured rate coefﬁcient ratio k(HO + CH CF )/k(HO + CH ) = (0.43± 0.12) exp[−(223± 90)/T ] was placed on 3 3 4 −20 2.82 3 −1 −1 an absolute basis by use of the rate coefﬁcient k(HO + CH ) = 1.85 × 10 T exp(-987/T ) cm molecule s (IUPAC, current recommendation). (e) The measured rate coefﬁcient ratio k(HO + CH CF )/k(HO + CHF CF ) = (2.16± 0.14) exp[-(370± 21)/T ] was placed 3 3 2 3 −19 2 3 −1 on an absolute basis by use of the rate coefﬁcient k(HO + CHF CF ) = 9.24× 10 T exp(-1120/T ) cm molecule 2 3 −1 s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 9.2× 10 exp(-1970/T ) cm molecule s over the temperature range 220-300 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 300 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4176 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The room temperature absolute rate coefﬁcients of Martin and Paraskevopoulos (1983) and Talukdar et al. (1991) agree to within 20%, and taking into account the respective uncertainties in both studies, the agreement is reasonable. The rate coefﬁcients of Hsu and DeMore, (1995) relative to the rate coefﬁcients for the reactions of the HO radical with CH and CHF CF , are in excellent agreement with each other. The rate coefﬁcients of Orkin et al. (1996) are also in quite good 2 3 agreement with the rate coefﬁcients of Talukdar et al. (1991) and both sets of relative rate coefﬁcients determined by Hsu and DeMore (1995). The rate coefﬁcients of Clyne and Holt (1979) are not used in the evaluation because their rate coefﬁcients at 333 K and 378 K are signiﬁcantly higher than those of the other studies and have large associated uncertainties. The rate coefﬁcients of Martin and Paraskevopoulos (1983), Talukdar et al. (1991) (using their entire data set over the temperature range 223–374 K), Orkin et al. (1996), and Hsu and DeMore (1995) have been ﬁtted to the three parameter 2 −18 2 3 −1 −1 equation k = CT exp(-D/T ), resulting in k = 1.91× 10 T exp(-1456/T ) cm molecule s over the temperature range 223–403 K. The preferred Arrhenius expression k = A exp(-B/T ), is centered on a mid-range temperature, T , of 255 K and 2 2 is derived from the three parameter equation with A = C e T and B = D+ 2T . The preferred values are 13% lower and 9% higher than the values of Talukdar et al. (1991) at 223 K and 261 K, respectively. References Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Martin, J.-P. and Paraskevopoulos, G.: Can. J. Chem. 61, 861, 1983. Orkin, V. L., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem. 100, 8907, 1996. Talukdar, R., Mellouki, A., Gierczak, T., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 95, 5815, Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4177 IV.A1.17 HO + CH FCH F→ H O + CH FCHF 2 2 2 2 ◦ −1 1H = -69.5 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (1.12± 0.12)× 10 298 Martin and Paraskevopoulos, 1983 FP-RA −12 5.11× 10 exp[-(1190± 106)/T ] 298-480 Kozlov et al., 2003 FP-RF −12 1.02× 10 exp[-(706± 70)/T ] 210-298 −14 (9.92± 0.18)× 10 298 Relative Rate Coefﬁcients −18 2 4.77× 10 T exp[-(454± 23)/T ] 293-397 Wilson et al., 2003 RR (a,b) −14 9.23× 10 298 −18 2 2.15× 10 T exp[-(188± 29)/T ] 287-409 Wilson et al., 2003 RR (a,c) −13 1.20× 10 298 −18 2 4.68× 10 T exp[-(441± 16)/T ] 292-393 Wilson et al., 2003 RR (a,d) −14 9.46× 10 298 Comments (a) Relative rate method. HO radicals were generated by photolyzing H O vapor at 185 nm. Reactant and reference com- pound concentrations were monitored by GC/MS. (b) Relative to C H . An Arrhenius plot of the data gives the temperature dependence of the measured ratios as (0.32± 0.02) 2 6 −17 2 exp[(45 ± 23)/T ], which is placed on an absolute basis using a rate coefﬁcient of k(HO + C H ) = 1.49 × 10 T 2 6 3 −1 −1 exp(-499/T ) cm molecule s (IUPAC, current recommendation). (c) Relative to cyclopropane. An Arrhenius plot of the data gives the temperature dependence of the measured ratios as (0.51 ± 0.04) exp[(266 ± 29)/T ] ], which is placed on an absolute basis using a rate coefﬁcient of k(HO + cyclopropane) = −18 2 3 −1 −1 4.21× 10 T exp(-454/T ) cm molecule s (Atkinson, 2003). (d) Relative to CH CHF . An Arrhenius plot of the data gives the temperature dependence of the measured ratios as (1.67 3 2 ± 0.08) exp[(139± 16)/T ], which is placed on an absolute basis using a rate coefﬁcient of k(HO + CH CHF ) = 2.80× 3 2 −18 2 3 −1 −1 10 T exp(-580/T ) cm molecule s (IUPAC, current recommendation). Preferred Values −13 3 −1 −1 k = 1.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.5× 10 exp(-800/T ) cm molecule s over the temperature range 210-300 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 200 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4178 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The absolute rate coefﬁcients of Kozlov et al. (2003) and the relative rate coefﬁcients of Wilson et al. (2003) (relative to C H and CH FCH F) are in good agreement over the temperature range 298–380 K. The absolute rate coefﬁcient of Martin 2 6 2 2 and Paraskevopoulos (1983) at 298 K agrees to within 20% or better to the data of Kozlov et al. (2003) and Wilson et al. (2003) (relative to C H and CH CHF ). The rate coefﬁcients of Wilson et al. (2003) relative to cyclopropane exhibit a lower 2 6 3 2 temperature dependence compared with the data of Kozlov et al. (2003) and the two other relative rate studies performed by Wilson et al. (2003). This may be due to the literature rate coefﬁcient for HO + cyclopropane being not well established because of substantial scatter in the literature data. Therefore, the rate coefﬁcients of Wilson et al. (2003) relative to cyclopropane were not used in the evaluation. The absolute rate coefﬁcients of Kozlov et al. (2003) and Martin and Paraskevopoulos (1983), and the relative rate coef- ﬁcients of Wilson et al. (2003) relative to C H and CH CHF have been ﬁtted to the three parameter equation k = CT 2 6 3 2 −18 2 3 −1 −1 exp(-D/T ) resulting in k = 3.39 × 10 T exp(-312/T ) cm molecule s over the temperature range 210–480 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 245 K and is derived from 2 2 the three parameter equation with A = C e T and B = D+ 2T . References Atkinson, R.: Atmos. Chem. Phys. 3, 2233, 2003. Kozlov, S. N., Orkin, V. L. and Kurylo, M. J.: J. Phys. Chem. A. 107, 2239, 2003. Martin, J.-P. and Paraskevopoulos, G.: Can. J. Chem. 61, 861, 1983. Wilson, E. W., Jr., Jacoby, A. M., Kukta, S. J., Gilbert, L. E. and DeMore, W. B.: J. Phys. Chem. A. 107, 9357, 2003. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4179 IV.A1.18 HO + CH FCHF → H O + CH FCF (1) 2 2 2 2 2 → H O + CHFCHF (2) 2 2 ◦ −1 1H (1) = -78.0 kJ·mol ◦ −1 1H (2) = -80.1 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 1.48× 10 exp[-(1000± 100)/T ] 293-425 Clyne and Holt, 1979 DF-RF −14 (4.68± 0.40)× 10 294 −14 (1.83± 0.18)× 10 298 Martin and Paraskevopoulos, 1983 FP-RA Relative Rate Coefﬁcients −18 2 4.97× 10 T exp(-1012/T ) 278-323 Barry et al., 1995 RR (a) −14 (1.49± 0.05)× 10 298± 2 Comments (a) HO radicals were generated by the photolysis of O in the presence of water vapor at ∼250 nm at atmospheric pressure of air. Irradiations of O -H O-CH FCHF -CH CCl -air mixtures were carried out and the concentrations of CH FCHF 3 2 2 2 3 3 2 2 and CH CCl measured by GC and FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CH FCHF )/k(HO 3 3 2 2 + CH CCl ) = 2.21 exp(-102/T ) is placed on an absolute basis by use of a rate coefﬁcient of k(HO + CH CCl ) = 2.25× 3 3 3 3 −18 2 3 −1 −1 10 T exp(-910/T ) cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 1.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 3.3× 10 exp(-1610/T ) cm molecule s over the temperature range 270-330 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The rate coefﬁcient of Martin and Paraskevopoulos (1983) at 298 K is∼25% higher than the 298 K value Barry et al. (1995). The preferred rate coefﬁcients are therefore derived from the relative rate study of Barry et al. (1995). The preferred Arrhenius −18 2 expression, k = A exp(-B/T ), is derived from the three parameter expression cited in the table (k = 4.97 × 10 T exp(- 3 −1 −1 1012/T ) cm molecule s over the temperature range 278–323 K) and is centered on a mid-range temperature, T , of 300 2 2 K with A = C e T and B = D+ 2T . References Barry, J., Sidebottom, H., Treacy, J. and Franklin, J.: Int. J. Chem. Kinet. 27, 27, 1995. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Martin, J.-P. and Paraskevopoulos, G.: Can. J. Chem. 61, 861, 1983. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4180 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.19 HO + CH FCF → H O + CHFCF 2 3 2 3 ◦ −1 1H = -63.1 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 3.2× 10 exp[-(1800± 200)/T ] 294-429 Clyne and Holt, 1979 DF-RF −15 (5.5± 0.7)× 10 294 −15 (5.2± 0.6)× 10 298 Martin and Paraskevopoulos, 1983 FP-RA −12 1.1× 10 exp[-(1424± 35)/T ] 249-473 Jeong et al., 1984 DF-RF −15 (8.44± 0.73)× 10 298 −12 5.8× 10 exp[-(1350)/T ] 231-423 Brown et al., 1990 DF-RF −15 6.25× 10 298 −12 3.7× 10 exp[-(1990± 280)/T ] 270-400 Liu et al., 1990 FP-RF −15 (5.18± 0.70)× 10 298 −13 5.7× 10 exp[-(1430± 60)/T ] 223-324 Gierczak et al., 1991 DF-LMR/FP-LIF (a) −15 (4.34± 0.35)× 10 298 −15 (2.38± 0.22)× 10 270 Zhang et al., 1992 DF-RF −12 1.03× 10 exp[-(1588± 52)/T ] 298-460 Orkin and Khamaganov, 1993 DF-EPR −15 (5.00± 0.44)× 10 298 −13 9.9× 10 exp[-(1640± 150)/T ] 255-424 Leu and Lee, 1994 DF-RF −15 (3.9± 0.6)× 10 298 −15 (4.6± 0.5)× 10 295 Bednarek et al., 1996 LP-UVA Relative Rate Coefﬁcients −21 2.82 8.26× 10 T exp [-(905± 115)/T ] 298-358 DeMore, 1993 RR (b,c) −15 3.76× 10 298 −18 2 1.84× 10 T exp [-(1129± 44)/T ] 298-358 DeMore, 1993 RR (b,d) −15 3.70× 10 298 −18 2 1.93× 10 T exp [-(1132± 79)/T ] 298-358 DeMore, 1993 RR (b,e) −15 3.84× 10 298 −15 (3.90± 0.48)× 10 298± 2 Barry et al., 1995 RR (f) −15 (4.19± 0.19)× 10 298± 2 Barry et al., 1995 RR (g) Comments (a) Measurements were performed up to a temperature of 450 K. The Arrhenius expression only covers the temperature range 223–324 K to avoid curvature in the Arrhenius plot. (b) Relative rate method. HO radicals were generated by the irradiation of O -H O-O -Ar mixtures at 254 nm. The 3 2 2 CH FCF , CH , CH CCl , and CHF CF concentrations were monitored during the experiments by FTIR absorption 2 3 4 3 3 2 3 spectroscopy. The measured rate coefﬁcient ratios of k(HO + CH )/k(HO + CH FCF ) = (2.24 ± 0.78) exp[-(82 ± 4 2 3 115)/T ], k(HO + CH CCl )/k(HO + CH FCF ) = (1.22 ± 0.17) exp[(219 ± 44)/T ] and k(HO + CHF CF /k(HO + 3 3 2 3 2 3 CH FCF ) = (0.48± 0.12) exp[(12± 79)/T ] are placed on an absolute basis by use of rate coefﬁcients k(HO + CH ) = 2 3 4 −20 2.82 3 −1 −1 1.85 × 10 T exp(-987/T ) cm molecule s (IUPAC, current recommendation), k(HO + CH CCl ) = 2.25 × 3 3 −18 2 3 −1 −1 −19 10 T exp(-910/T ) cm molecule s (IUPAC, current recommendation) and k(HO + CHF CF ) = 9.24 × 10 2 3 2 3 −1 −1 T exp(-1120/T ) cm molecule s (IUPAC, current recommendation). (c) Relative to k(HO + CH ). Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4181 (d) Relative to k(HO + CH CCl ). 3 3 (e) Relative tok(HO + CHF CF ). 2 3 (f) Relative rate method. HO radicals were generated by the photolysis of O at∼250 nm in the presence of water vapor at atmospheric pressure of air. Irradiations of O -H O-CH FCF -CH CCl -air mixtures were carried out at 298± 2 K and 3 2 2 3 3 3 the concentrations of CH FCF and CH CCl measured by GC and FTIR spectroscopy. The measured rate coefﬁcient 2 3 3 3 ratio of k(HO + CH FCF )/k(HO + CH CCl ) = 0.41± 0.05 is placed on an absolute basis by using a rate coefﬁcient of 2 3 3 3 −15 3 −1 −1 k(HO + CH CCl ) = 9.5× 10 cm molecule s at 298 K (IUPAC, current recommendation). 3 3 (g) Relative rate method. HO radicals were generated by the photolysis of O in the presence of water vapor. Irradiations of O -H O-CH FCF -CH FCHF -air mixtures were carried out at 298 ± 2 K and the concentrations of CH FCF and 3 2 2 3 2 2 2 3 CH FCHF measured by GC and FTIR spectroscopy. The measured rate coefﬁcient ratio k(HO + CH FCHF )/k(HO + 2 2 2 2 −14 CH FCF ) = 3.58± 0.16 is placed on an absolute basis by using a rate coefﬁcient of k(HO + CH FCHF ) = 1.5× 10 2 3 2 2 3 −1 −1 cm molecule s at 298 K (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 4.6× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 4.9× 10 exp(-1395/T ) cm molecule s over the temperature range 220-300 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The absolute rate coefﬁcient of Zhang et al. (1992) at 270 K is in good agreement with those of Liu et al. (1990), Gierczak et al. (1991) and Leu and Lee (1994) over the temperature range 270–273 K. The absolute rate coefﬁcients of Orkin and Khamaganov (1993) are in agreement with those of Gierczak et al. (1991) and Leu and Lee (1994). At 298 K, the relative rate coefﬁcients of DeMore (1993) and Barry et al. (1995) are lower than the absolute rate coefﬁcients of Martin and Paraskevopoulos (1983), Liu et al. (1990), Gierczak et al. (1991) and Orkin and Khamaganov (1993) by up to 30%. On the other hand, the absolute rate coefﬁcients of Leu and Lee (1994) are in good agreement with the relative rate coefﬁcients of DeMore (1993) and Barry et al. (1995), and are between 10-20% lower than the absolute rate coefﬁcients of Gierczak et al. (1991) and Orkin and Khamaganov (1993). Above 298 K, the absolute rate coefﬁcients of Liu (1990) are up to 30% higher than those of Gierczak et al. (1991). The high rate coefﬁcients of Clyne and Holt (1979), Brown et al. (1990) and Jeong et al. (1984) were not used in the evaluation. The absolute rate coefﬁcients of Martin and Paraskevopoulos (1983), Liu et al. (1990), Gierczak et al. (1991), Zhang et al. (1992), Orkin and Khamaganov (1993), Leu and Lee (1994), Bednarek et al. (1996), and the relative rate coefﬁcients of 2 −18 2 Barry et al. (1995) have been ﬁtted to the three parameter equation k = CT exp(-D/T ), giving k = 1.0 × 10 T exp(- 3 −1 −1 885/T ) cm molecule s over the temperature range 220–460 K. The preferred Arrhenius expression, k = A exp(-B/T ), is 2 2 centered on a mid-range temperature, T , of 255 K and is derived from the three parameter equation with A = C e T and B = D + 2T . This expression yields rate coefﬁcients that are 10-15% higher than those calculated from the rate coefﬁcient expressions tabulated for DeMore (1993). References Barry, J., Sidebottom, H., Treacy, J. and Franklin, J.: Int. J. Chem. Kinet. 27, 27, 1995. Bednarek, G., Breil, M., Hoffmann, A., Kohlmann, J. P., Mors, V. and Zellner, R.: Ber. Bunsenges. Phys. Chem. 100, 528, Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ. 24A, 2499, 1990. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. DeMore, W. B.: Geophys. Res. Lett. 20, 1359, 1993. Gierczak, T., Talukdar, R., Vaghjiani, G. L., Lovejoy, E. R. and Ravishankara, A. R.: J. Geophys. Res. 96, 5001, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4182 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem. 88, 1222, 1984. Leu, G.-H. and Lee, Y.-P.: J. Chin. Chem. Soc. 41, 645, 1994. Liu, R., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem. 94, 3247, 1990. Martin, J.-P. and Paraskevopoulos, G.: Can. J. Chem. 61, 861, 1983. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem. 16, 157, 1993. Zhang, Z., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem. 96, 1533, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4183 IV.A1.20 HO + CHF CHF → H O + CF CHF 2 2 2 2 2 ◦ −1 1H = -58.41 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 2.76× 10 exp[-(1800± 400)/T ] 294-434 Clyne and Holt, 1979 DF-RF −15 6.57× 10 298 Relative Rate Coefﬁcients −18 2 2.67× 10 T exp[-(1122± 37)/T ] 298-358 DeMore, 1993 RR (a) −15 5.50× 10 298 −18 2 1.18× 10 T exp[-(805± 25)/T ] 298-358 DeMore, 1993 RR (b) −15 7.0× 10 298 −18 2 1.93× 10 T exp[-(1011± 77)/T ] 298-358 DeMore, 1993 RR (c) −15 5.76× 10 298 Comments (a) HO radicals were generated by the photolysis of O -H O-O -Ar mixtures at 254 nm. The concentrations of CHF CHF 3 2 2 2 2 and CH CCl were measured during the experiments by FTIR absorption spectroscopy. The measured rate coefﬁcient 3 3 ratio of k(HO + CH CCl )/k(HO + CHF CHF ) = (0.84 ± 0.10) exp[(212 ± 37)/T ] is placed on an absolute basis by 3 3 2 2 −18 2 3 −1 −1 use of a rate coefﬁcient of k(HO + CH CCl ) = 2.25 × 10 T exp(-910/T ) cm molecule s (IUPAC, current 3 3 recommendation). (b) HO radicals were generated by the photolysis of O -H O-O -Ar mixtures at 254 nm. The concentrations of CHF CHF 3 2 2 2 2 and CH FCF were measured during the irradiations by FTIR absorption spectroscopy. The measured rate coefﬁcient 2 3 ratio of k(HO + CH FCF )/(k(HO + CHF CHF ) = (0.85 ± 0.07) exp[-(80 ± 25)/T ] is placed on an absolute basis 2 3 2 2 −18 2 3 −1 −1 by use of the rate coefﬁcient k(HO + CH FCF ) = 1.0 × 10 T exp(-885/T ) cm molecule s (IUPAC, current 2 3 recommendation). (c) HO radicals were generated by irradiation of O -H O-O -Ar mixtures at 254 nm. The concentrations of CHF CHF 3 2 2 2 2 and CHF CF were measured by FTIR absorption spectroscopy. The measured rate coefﬁcient ratio of k(HO + 2 3 CHF CF )/k(HO + CHF CHF ) = (0.48 ± 0.11) exp[-(109 ± 77)/T ] is placed on an absolute basis by use of the rate 2 3 2 2 −19 2 3 −1 −1 coefﬁcient k(HO + CHF CF ) = 9.24× 10 T exp(-1120/T ) cm molecule s (IUPAC, current recommendation). 2 3 Preferred Values −15 3 −1 −1 k = 6.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.4× 10 exp(-1620/T ) cm molecule s over the temperature range 290-360 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4184 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The relative rate coefﬁcients of DeMore (1993) using three reference compounds are in good agreement (within 20% over the temperature range 298–358 K). While the 298 K rate coefﬁcient of Clyne and Holt (1979) is also in good agreement with the relative rate coefﬁcients of DeMore (1993), the temperature dependence reported by Clyne and Holt (1979) is signiﬁcantly higher than those of DeMore (1993). The data of Clyne and Holt (1979) is also sparse and scattered. Therefore the data of Clyne and Holt (1979) are not used in the evaluation. The preferred 298 K rate coefﬁcient is an average of the three relative rate measurements of DeMore (1993). The relative rate coefﬁcients of DeMore (1993) were placed on an absolute basis and ﬁtted to the three parameter equation k = CT exp(-D/T ), −18 2 3 −1 −1 resulting in k = 1.80 × 10 T exp(-974/T ) cm molecule s over the temperature range 290–360 K. The preferred Arrhenius expression, k = A exp(-B/T ) is centered on a mid-range temperature, T , of 320 K and is derived from the three 2 2 parameter equation with A = C e T and B = D+ 2T . References Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. DeMore, W. B.: Geophys. Res. Lett. 20, 1359, 1993. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4185 IV.A1.21 HO + CHF CF → H O + CF CF 2 3 2 2 3 ◦ −1 1H = -54.1 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 1.70× 10 exp[-(1100± 100)/T ] 294-441 Clyne and Holt, 1979 DF-RF −15 (4.9± 1.4)× 10 294 −15 (2.49± 0.27)× 10 298 Martin and Paraskevopoulos, 1983 FP-RA −13 2.8× 10 exp[-(1350± 100)/T ] 257-423 Brown et al., 1990 DF-RF −15 (2.69± 0.93)× 10 298 −13 5.41× 10 exp[-(1700± 100)/T ] 220-364 Talukdar et al., 1991 DF-LMR/PLP-LIF −15 (1.90± 0.27)× 10 298 Relative Rate Coefﬁcients −15 (1.64± 0.21)× 10 298 DeMore, 1992 RR (a) Comments (a) HO radicals were generated by the photolysis of O in the presence of water vapor at 254 nm. Irradiations of O -H O- 3 3 2 CHF CF -CH -O -N (or Ar) mixtures were carried out, and the concentrations of CHF CF and the CH were measured 2 3 4 2 2 2 3 4 by FTIR absorption spectroscopy. The measured rate coefﬁcient ratio k(HO + CH )/k(HO + CF CHF ) = 3.9 ± 0.50 is 4 3 2 −15 3 −1 −1 placed on an absolute basis by use of the rate coefﬁcient k(HO + CH ) = 6.4 × 10 cm molecule s at 298 K (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 1.9× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 4.4× 10 exp(-1630/T ) cm molecule s over the temperature range 220–300 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The relatively high results of Clyne and Holt (1979) and Brown et al. (1990) suggest the presence of reactive impurities in the CHF CF samples used in their studies. These data were therefore not used in the evaluation. At 298 K, the rate coefﬁcients 2 3 of DeMore (1992) and Talukdar et al. (1991) agree to within 10%; the rate coefﬁcient of Martin and Paraskevopoulos (1983) is 30% higher than the corresponding value of Talukdar et al. (1991). The rate coefﬁcient data of Martin and Paraskevopoulos (1983), Talukdar et al. (1991) and DeMore (1992) were ﬁtted to the three parameter equation k = CT exp(-D/T ), resulting −19 2 3 −1 −1 in k = 9.24 × 10 T exp(-1120/T ) cm molecule s over the temperature range 220–360 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 255 K and is derived from the three parameter 2 2 equation with A = C e T and B = D+ 2T . www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4186 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ. 24A, 2499, 1990. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. DeMore, W. B.: Optical Methods in Atmospheric Chemistry, Soc. Photo-Optic Instrum. Eng. 1715, 72, 1992. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Martin, J.-P. and Paraskevopoulos, G.: Can. J. Chem. 61, 861, 1983. Talukdar, R., Mellouki, A., Gierczak, T., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 95, 5815, Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4187 IV.A1.22 HO + CHF CF CH F → H O + CHF CF CHF (1) 2 2 2 2 2 2 → H O + CF CF CH F (2) 2 2 2 2 Rate coefﬁcient data(k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 2.87× 10 exp[-(1661± 170)/T ] 260-365 Zhang et al., 1994 FP-RF −14 (1.09± 0.03)× 10 298 Relative Rate Coefﬁcients −20 2.82 1.24× 10 T exp[-(823± 34)/T ] 286-364 Hsu and DeMore, 1995 RR (a) −15 7.44× 10 298 Comments (a) Relative rate method. HO radicals were generated by the photolysis of H O at 185 nm or of O -H O mixtures in the 2 3 2 UV in H O (or H O-O )-CHF CF CH F-CH -O -N mixtures. The concentrations of CHF CF CH F and CH were 2 2 3 2 2 2 4 2 2 2 2 2 4 measured by FTIR absorption spectroscopy. The measured rate coefﬁcient of k(HO + CHF CF CH F)/k(HO + CH ) = 2 2 2 4 (0.67 ± 0.07) exp[(164 ± 34)/T ] is placed on an absolute basis by use of a rate coefﬁcient of k(HO + CH ) = 1.85 × −20 2.82 3 −1 −1 10 T exp(-987/T) cm molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 7.7× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.2× 10 exp(-1685/T ) cm molecule s over the temperature range 285-365 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The relative rate coefﬁcients of Hsu and DeMore (1995) are uniformly a factor of 1.5 lower than the absolute rate coefﬁcients of Zhang et al. (1994) over the temperature range common to both studies (286–364 K). This suggests the presence of reactive impurities or of secondary reactions in the study of Zhang et al. (1994). The relative rate coefﬁcients of Hsu and DeMore (1995) were used to derive the preferred values. These data were ﬁtted to the three parameter equation, k = CT exp(-D/T ), −18 2 3 −1 −1 resulting in k = 2.84 × 10 T exp(-1045/T ) cm molecule s over the temperature range 285–365 K. The preferred Arrhenius expression, k = A exp(B/T ), is centered on a mid-range temperature, T , of 320 K and is derived from the three 2 2 parameter equation with A = C e T and B = D+ 2T . References Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Zhang, Z., Padmaja, S., Saini, R. D., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem. 98, 4312, 1994. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4188 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.23 HO + CF CF CH F→ H O + CF CF CHF 3 2 2 2 3 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 2.6× 10 exp[-(1107± 202)/T ] 256-314 Garland et al., 1993 PLP-LIF −15 (6.4± 0.6)× 10 295 Preferred Values −15 3 −1 −1 k = 6.5× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 2.6× 10 exp(-1100/T ) cm molecule s over the temperature range 250-320 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The preferred values are derived from the sole study of Garland et al. (1993). References Garland, N. L., Medhurst, L. J. and Nelson, H. H.: J. Geophys. Res. 98, 23107, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4189 IV.A1.24 HO + CF CHFCHF → H O + CF CFCHF (1) 3 2 2 3 2 → H O + CF CHFCF (2) 2 3 2 Rate coefﬁcient data(k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 2.0× 10 exp[-(1007± 151)/T ] 251-311 Garland et al., 1993 PLP-LIF −15 (6.5± 0.5)× 10 294 −12 1.05× 10 exp[-(1434± 161)/T ] 260-365 Zhang et al., 1994 FP-RF −15 (8.51± 0.26)× 10 298 −15 (4.93± 0.25)× 10 294 Nelson et al., 1995 DF-LIF Relative Rate Coefﬁcients −21 2.82 6.7× 10 T exp[-(756± 12)/T ] 298-380 Hsu and DeMore, 1995 RR (a) −15 5.0× 10 298 Comments (a) HO radicals were generated by the photolysis of H O at 185 nm or of O -H O mixtures in the UV, in H O (or O -H O)- 2 3 2 2 3 2 CF CHFCHF -CH -O -N mixtures. The concentrations of CF CHFCHF and CH were measured by FTIR absorption 3 2 4 2 2 3 2 4 spectroscopy. The measured rate coefﬁcient ratio of k(HO + CF CHFCHF )/k(HO + CH ) = (0.36 ± 0.01) exp[(231 ± 3 2 4 −20 2.82 3 12)/T ] is placed on an absolute basis by using a rate coefﬁcient of k(HO + CH ) = 1.85× 10 T exp(-987/T ) cm −1 −1 molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 5.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.4× 10 exp(-1680/T ) cm molecule s over the temperature range 290-380 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The preferred values are derived from the relative rate coefﬁcients of Hsu and DeMore (1995) and the absolute rate study by Nelson et al. (1995). These data were ﬁtted to the three parameter equation, k = CT exp(-D/T ), resulting in k = 1.76 × −18 2 3 −1 −1 10 T exp(-1021/T ) cm molecule s over the temperature range 294–380 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 330 K and is derived from the three parameter equation, k = A 2 2 exp(-B/T ) with A = Ce T and B = D+ 2T . The higher values of Garland et al. (1993) and Zhang et al. (1994) were not used in this evaluation as their experiments may have been subject to problems arising from the presence of impurities. References Garland, N. L., Medhurst, L. J. and Nelson, H. H.: J. Geophys. Res. 98, 23107, 1993. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Nelson, D. D., Jr., Zahniser, M. S., Kolb, C. E. and Magid, H.: J. Phys. Chem. 99, 16301, 1995. Zhang, Z., Padmaja, S., Saini, R. D., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem. 98, 4312, 1994. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4190 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.25 HO + CF CH CF → H O + CF CHCF 3 2 3 2 3 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 2.0× 10 exp[-(906± 151)/T ] 257-311 Garland et al., 1993 PLP-LIF −16 9.6× 10 298 −16 (5.1± 0.7)× 10 294 Nelson et al., 1995 DF-LIF −16 (4.15± 0.33)× 10 298 Garland and Nelson, 1996 PLP-LIF −12 (1.6± 0.4)× 10 exp[-(2540± 150)/T ] 273-413 Gierczak et al., 1996 FP-LIF −16 (3.20± 0.60)× 10 298 Relative Rate Coefﬁcients −18 2 1.16× 10 T exp[-(1700± 109)/T ] 298-367 Hsu and DeMore, 1995 RR (a) −16 3.43× 10 298 −16 (3.5± 1.5)× 10 298 Barry et al., 1997 RR (b) Comments (a) Relative rate method. HO radicals were generated from the photolysis of H O at 185 nm or of O -H O mixtures in the 2 3 2 UV in H O (or O -H O)-CF CH CF -CHF CF -O -N mixtures. The concentrations of CF CH CF and CHF CF 2 3 2 3 2 3 2 3 2 2 3 2 3 2 3 were measured by FTIR absorption spectroscopy. The measured rate coefﬁcient ratio of k(HO + CF CH CF )/k(HO + 3 2 3 CHF CF ) = (1.26 ± 0.41) exp[-(580 ± 109)/T ] is placed on an absolute basis by using a rate coefﬁcient of k(HO + 2 3 −19 2 3 −1 −1 CHF CF ) = 9.24× 10 T exp(-1120/T ) cm molecule s (IUPAC, current recommendation). 2 3 (b) Relative rate method. HO radicals were generated by UV photolysis of O at 254 nm in the presence of H O vapour. 3 2 Mixtures of O /CF CH CF /CF CH CF CH /H O were photolysed in air at 298 K, k(HO + CF CH CF )/k(HO + 3 3 2 3 3 2 2 3 2 3 2 3 CF CH CF CH ) was found to be 0.06 ± 0.02. Using the experimentally derived value of k(HO + CF CH CF CH ) 3 2 2 3 3 2 2 3 −12 3 −1 −1 −16 3 = 2.0 × 10 exp[-(1750 ± 400)/T ] cm molecule s gives k(HO + CF CH CF ) = (3.5 ± 1.5) × 10 cm 3 2 3 −1 −1 molecule s . Preferred Values −16 3 −1 −1 k = 3.3× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.3× 10 exp(-2465/T ) cm molecule s over the temperature range 270–340 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The preferred values are derived from the relative rate coefﬁcients of Hsu and DeMore (1995) and the absolute rate coefﬁcients of Gierczak et al. (1996). The agreement between the data of Hsu and DeMore (1995), when placed on an absolute basis as described above, and the data of Gierczak et al. (1996) is very good over the temperature range 298-367 K. The absolute rate coefﬁcients of Garland et al. (1993) over the temperature range 257-311 K are consistently higher than those of Hsu and Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4191 DeMore (1995) and Gierczak et al. (1996) and were not used in the evaluation. The absolute rate coefﬁcient of Nelson et al. (1995) is also relatively large and has a large uncertainty; this value was also not used in the evaluation. The data of Hsu and DeMore (1995) and Gierczak et al. (1996) were ﬁtted to the three parameter equation, k = CT −18 2 3 −1 −1 exp(-D/T ), resulting in k = 1.91× 10 T exp(-1865/T ) cm molecule s over the temperature range 273–413 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 300 K and is derived from 2 2 the three-parameter equation with A = Ce T and B = D+ 2T . Note that the preferred Arrhenius expression should not be used outside the speciﬁed temperature range (270–340 K); rather, the full three parameter expression should be used. The relative rate study of Barry et al. (1997) at 298 K is in very good agreement with the recommended value. However, the very small rate constant ratio would lead to large uncertainties, therefore the rate coefﬁcient derived by Barry et al. (1997) was not used in the evaluation. The preferred value at 298 K is 30% lower than the absolute rate coefﬁcient of Garland and Nelson (1996), but taking into account the uncertainty in the Garland and Nelson (1996) value, the agreement is reasonable. References Barry, J., Locke, G., Scollard, D., Sidebottom, H., Treacy, J., Clerbaux, C., Colin, R. and Franklin, J.: Int. J. Chem. Kinet. 29, 607, 1997. Garland, N. L., Medhurst, L. J. and Nelson, H. H.: J. Geophys. Res. 98, 23107, 1993. Garland, N. L. and Nelson, H. H.: Chem. Phys. Lett. 248, 296, 1996. Gierczak, T., Talukdar, R. K., Burkholder, J. B., Portmann, R. W., Daniel, J. S., Solomon, S. and Ravishankara, A. R.: J. Geophys. Res. 101, 12905, 1996. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Nelson, D. D., Jr., Zahniser, M. S., Kolb, C. E. and Magid, H.: J. Phys. Chem. 99, 16301, 1995. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4192 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.26 HO + CF CHFCF → H O + CF CFCF 3 3 2 3 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 3.7× 10 exp[-(1615± 190)/T ] 294-369 Nelson et al., 1993 DF-LIF −15 (1.64± 0.28)× 10 295 −13 3.8× 10 exp[-(1596± 77)/T ] 298-463 Zellner et al., 1994 PLP-LIF −15 (1.8± 0.2)× 10 298 −13 3.63× 10 exp[-(1613± 135)/T ] 270-365 Zhang et al., 1994 FP-RF −15 (1.62± 0.03)× 10 298 −13 6.19× 10 exp[-(1830± 100)/T ] 250-430 Tokuhashi et al., 2004 FP/PLP-LIF (a) −15 (1.34± 0.08)× 10 298 Relative Rate Coefﬁcients −21 2.82 3.15× 10 T exp[-(870± 105)/T ] 296-398 Hsu and DeMore, 1995 RR (b,c) −15 1.55× 10 296 −19 2 7.67× 10 T exp[-(1082± 89)/T ] 298-367 Hsu and DeMore, 1995 RR (b,d) −15 1.80× 10 298 Comments (a) HO radical concentration monitored by laser induced ﬂuorescence. (b) Relative rate method. HO radicals were generated by the photolysis of H O at 185 nm or O at 254 nm, in H O (or O - 2 3 2 3 H O) - CF CHFCF - CH (or CHF CF )- O - N mixtures. The concentrations of CF CHFCF and CH (or CHF CF ) 2 3 3 4 2 3 2 2 3 3 4 2 3 were measured by FTIR absorption spectroscopy. The measured rate coefﬁcient ratios of k(HO + CF CHFCF )/k(HO + 3 3 CH ) = (0.17 ± 0.05) exp[(117 ± 105)/T ] and k(HO + CF CHFCF )/ k(HO + CHF CF ) = (0.83 ± 0.22) exp[(38 ± 4 3 3 2 3 −20 2.82 89)/T ] are placed on an absolute basis by use of rate coefﬁcients of k(HO + CH ) = 1.85 × 10 T exp(-987/T ) 3 −1 −1 −19 2 3 cm molecule s (IUPAC, current recommendation) and k(HO + CHF CF ) = 9.24 × 10 T exp(-1120/T ) cm 2 3 −1 −1 molecule s (IUPAC, current recommendation). (c) Relative to k(HO + CH ). (d) Relative to k(HO + CHF CF ). 2 3 Preferred Values −15 3 −1 −1 k = 1.4× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 5.3× 10 exp(-1770/T ) cm molecule s over the temperature range 250-380 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4193 Comments on Preferred Values The preferred values are derived from absolute rate coefﬁcients of Zhang et al. (1994) and Tokuhashi et al. (2004). The relative rate coefﬁcients of Hsu and DeMore (1995), and the absolute rate coefﬁcients of Nelson et al. (1993) and Zellner et al. (1994) are 10-30% higher than those of Tokuhashi et al. (2004) over the temperature range 298–380 K, with the agreement being better at the higher temperatures. Tokuhashi et al. (2004) used highly puriﬁed reactants in their study, suggesting that the previous studies may have been affected by reactant impurities. The data of Zellner et al. (1994), Zhang et al. (1994) and Tokuhashi et al. (2004) were ﬁtted to the three parameter equation, 2 −19 2 3 −1 −1 k = CT exp(-D/T ), resulting in k = 8.0× 10 T exp(-1170/T ) cm molecule s over the temperature range 250–430 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 300 K and is derived 2 2 from the three parameter equation with A = Ce T and B = D + 2T . Note that the preferred Arrhenius expression should not be used outside the speciﬁed temperature range (250–380 K); rather, the full three parameter expression should be used. References Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Nelson Jr., D. D., Zahniser, M. S. and Kolb, C. E.: Geophys. Res. Lett. 20, 197, 1993. Tokuhashi, K., Chen, L., Kutsuna, S., Uchimaru, T., Sugie, M. and Sekiya, A.: J. Fluorine Chemistry 125, 1801, 2004. Zellner, R., Bednarek, G., Hoffmann, A., Kohlmann, J. P., Mors, V. and Saathoff, H.: Ber. Bunsenges. Phys. Chem. 98, 141, Zhang, Z., Padmaja, S., Saini, R. D., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem. 98, 4312, 1994. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4194 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.27 HO + CHF OCHF → H O + CHF OCF 2 2 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (2.47± 0.2)× 10 296 Zhang et al., 1992 FP-RF −13 5.4× 10 exp[-(1560± 200)/T ] 269-312 Garland et al., 1993 LP-LIF −15 (3.0± 0.7)× 10 295 −13 6.3× 10 exp[-(1646± 76)/T ] 277-370 Orkin et al., 1999 FP-RF −15 (2.52± 0.17)× 10 298 Relative Rate Coefﬁcients −18 2 2.36× 10 T exp[-(1366± 62)/T ] 298-368 Hsu and DeMore, 1995 RR (a) −15 2.1× 10 298 −18 2 2.12× 10 T exp[-(1313± 10)/T ] 273-465 Wilson et al., 2001 RR (b) −15 2.29× 10 298 Comments (a) HO radicals were generated from the photolysis of H O at 185 nm or O at 254 nm in the presence of H O. The concen- 2 3 2 trations of CHF OCHF and CH CCl were measured by FTIR absorption spectroscopy. The measured rate coefﬁcient 2 2 3 3 ratio of k(HO + CHF OCHF )/k(HO + CH CCl ) = (1.05± 0.20) exp[-(456± 62)/T ] is placed on an absolute basis by 2 2 3 3 −18 2 3 −1 −1 using the rate coefﬁcient for k(HO + CH CCl ) = 2.25 × 10 T exp(-910/T ) cm molecule s (IUPAC, current 3 3 recommendation). (b) HO radicals were generated from the photolysis of H O vapour in the reaction mixture at 185 nm. The concentrations of CHF OCHF and CF CHF were monitored by GCMS. An Arrhenius plot of the Wilson et al. (2001) data gives a 2 2 3 2 rate coefﬁcient ratio of k(HO + CHF OCHF )/k(HO + CF CHF ) = (2.29± 0.06) exp[-(193± 10)/T ] over the temper- 2 2 3 2 ature range 273–465 K. The rate coefﬁcient ratio was placed on an absolute basis by using a rate coefﬁcient of k(HO + −19 2 3 −1 −1 CHF CF ) = 9.24× 10 T exp(-1120/T ) cm molecule s (IUPAC, current recommendation) 2 3 Preferred Values −15 3 −1 −1 k = 2.2× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.9× 10 exp(-2020/T ) cm molecule s over the temperature range 270-460 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The absolute rate coefﬁcients of Orkin et al. (1999) and the relative rate coefﬁcients of Hsu and DeMore (1995) and Wilson et al. (2001) are in good agreement over the temperature range 273–370 K. The 296 K rate coefﬁcient of Zhang et al. (1992) is an order of magnitude higher than all other values, presumably due to the presence of impurities in their CHF OCHF samples. 2 2 The measurements of Garland et al. (1993) are scattered. Thus, neither the data of Zhang et al. (1992) nor the data of Garland et al. (1993) were used in the evaluation. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4195 The preferred values were obtained from the rate coefﬁcient data of Hsu and DeMore (1995), Orkin et al. (1999) and Wilson et al. (2001). These rate coefﬁcient data were ﬁtted to the three-parameter equation k = CT exp(-D/T ), resulting in k = 2.22 −18 2 3 −1 −1 × 10 T exp(-1338/T ) cm molecule s over the temperature range 273–464 K. The preferred Arrhenius expression, k 2 2 = A exp(-B/T ), is centered on a mid-range temperature, T , of 340 K with A = Ce T and B = D+ 2T . m m Good et al. (1999) have performed experiments and ab initio calculations to determine the mechanism of CHF OCHF 2 2 oxidation under atmospheric conditions (no kinetic data was reported). Activation barriers were calculated for various steps, and an oxidation mechanism was described. References Garland, N. L., Medhurst, L. J. and Nelson, H. H.: J. Geophys. Res. 98, 23107, 1993. Good, D. A., Kamboures, M., Santiano, R. and Francisco, J. S.: J. Phys. Chem. A. 103, 9230, 1999. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 11141, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Orkin, V. L., Villenave, E., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem. A. 103, 9770, 1999. Wilson, E. W., Jr., Sawyer, A. A. and Sawyer, H. A.: J. Phys. Chem. A. 105, 1445, 2001. Zhang, Z., Saini, R. D., Kurylo, M. J. and Huie, R. E.: J. Phys. Chem. 96, 105, 9301, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4196 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.28 HO + HC(O)F→ H O + FCO ◦ −1 1H = -56.2 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −15 < 5.0× 10 296± 2 Wallington and Hurley, 1993 RR (a) Comments (a) HO radicals were generated from the photolysis of O -H -O mixtures, and HC(O)F was formed in situ from the oxidation 3 2 2 of CH F. No losses of HC(O)F were observed, leading to a rate coefﬁcient ratio of k(HO + HC(O)F)/k(HO + CH F) < 3 3 −14 0.25. This upper limit to the rate coefﬁcient ratio is placed on an absolute basis by use of k(HO + CH F) = 2.0× 10 3 −1 −1 cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k < 1.0× 10 cm molecule s at 298 K. Comments on Preferred Values The preferred value is derived from the sole study of Wallington and Hurley (1993), with the higher upper limit reﬂecting uncertainties in the reference reaction rate coefﬁcient. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Wallington, T. J. and Hurley, M. D.: Environ. Sci. Technol. 27, 1448, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4197 IV.A1.29 HO + CHF CHO → H O + CHF CO (1) 2 2 2 → H O + CF CHO (2) 2 2 ◦ −1 1H (1) = -110.4 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (1.7± 0.2)× 10 298± 2 Scollard et al., 1993 PLP-RF Relative Rate Coefﬁcients −12 (1.3± 0.3)× 10 298± 2 Scollard et al., 1993 RR (a) −12 (1.8± 0.4)× 10 298± 2 Sellevag ˚ et al., 2005 RR (b) Comments (a) HO radicals were generated by the photolysis of CH ONO (or C H ONO)-NO-CHF CHO-toluene-air mixtures at 1 bar 3 2 5 2 pressure. The concentrations of CHF CHO and toluene were measured by GC and FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHF CHO)/k(HO + toluene) is placed on an absolute basis by using a rate coefﬁcient of −12 3 −1 −1 k(HO + toluene) = 5.63× 10 cm molecule s (Calvert et al., 2002). (b) HO radicals were generated by the photolysis of O in the presence of H -CHF CHO-propane-air mixtures at 1 bar 3 2 2 pressure. The concentrations of CHF CHO and propane were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHF CHO)/k(HO + C H ) = 1.62 ± 0.04 is placed on an absolute basis by using a rate 2 3 8 −12 3 −1 −1 coefﬁcient of k(HO + C H ) = 1.1× 10 cm molecule s (IUPAC, current recommendation) 3 8 Preferred Values −12 3 −1 −1 k = 1.6× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.2 at 298 K. Comments on Preferred Values The absolute and relative rate coefﬁcients of Scollard et al. (1993) and Sellevag ˚ et al. (2005) are in good agreement, and the preferred value is the average of these rate coefﬁcients. The reaction is expected to proceed by pathway (1) (Scollard et al., 1993), which is supported by the quantum chemical calculations of Sellevag ˚ et al. (2005). References Calvert, J. G., Atkinson, R., Becker, K. H., Kamens, R. M., Seinfeld, J. H., Wallington, T. J. and Yarwood, G.: The Mechanisms of Atmospheric Oxidation of Aromatic Hydrocarbons, Oxford University Press, New York, 2002. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Balestra-Garcia, C., Laverdet, G., Le Bras, G., MacLeod, H. and Teton, ´ S.: J. Phys. Chem. 97, 4683, 1993. Sellevag, S. R., Stenstrøm, Helgaker, T., and Nielsen, C. J.: J. Phys. Chem. A. 109, 3652, 2005. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4198 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.30 HO + CF CHO→ H O + CF CO 3 2 3 ◦ −1 1H = -107.2 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 ´ ´ (1.1± 0.7)× 10 299± 3 Dobe et al., 1989 DF-RF −13 (6.5± 0.5)× 10 298± 2 Scollard et al. 1993 PLP-RF Relative Rate Coefﬁcients −13 (4.4± 1.0)× 10 298± 2 Scollard et al. 1993 RR (a) −13 (4.8± 0.3)× 10 298± 2 Sellevag et al. 2004 RR (b) −13 (6.15± 0.80)× 10 296± 2 Sulbaek Anderson et al., 2004 RR (c,d) −13 (6.93± 0.81)× 10 296± 2 Sulbaek Anderson et al., 2004 RR (c,e) Comments (a) HO radicals were generated by the photolysis of CH ONO (or C H ONO)-NO-CF CHO-CH COCH -air mixtures at 1 3 2 5 3 3 3 bar pressure. The concentrations of CF CHO and CH COCH were measured by GC and FTIR spectroscopy. The mea- 3 3 3 sured rate coefﬁcient ratio of k(HO + CF CHO)/k(HO + CH C(O)CH ) = (2.43± 0.53) is placed on an absolute basis by 3 3 3 −13 3 −1 −1 use of a rate coefﬁcient of k(HO + CH C(O)CH ) = 1.8× 10 cm molecule s (IUPAC, current recommendation). 3 3 (b) HO radicals were generated by the photolysis of O in the presence of H at 1 bar pressure. FTIR was used to monitor 2 2 the disappearance of reactant and reference compound. The measured rate coefﬁcient ratio of k(HO + CF CHO)/k(HO −13 3 + C H ) = (2.00± 0.13) is placed on an absolute basis by use of a rate coefﬁcient of k(HO + C H ) = 2.4× 10 cm 2 6 2 6 −1 −1 molecule s (IUPAC, current recommendation). (c) HO radicals were generated by the photolysis of CH ONO in the presence of NO in air at a pressure of 933 mbar. The concentrations of CF CHO, C H , C H and reaction products were measured by FTIR spectroscopy. The measured rate 3 2 2 2 4 coefﬁcient ratios k(HO + CF CHO)/k(HO + C H ) and k(HO + CF CHO)/k(HO + C H ) were placed on an absolute 3 2 2 3 2 4 −13 3 −1 −1 basis by using k(HO + C H ) = 8.45× 10 cm molecule s at 296 K (Sørensen et al. 2003), and k(HO + C H ) = 2 2 2 4 −12 3 −1 −1 8.52× 10 cm molecule s at 296 K (Calvert et al. 2000). (d) Relative to C H . 2 2 (e) Relative to C H . 2 4 Preferred Values −13 3 −1 −1 k = 5.7× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.2 at 298 K. Comments on Preferred Values The preferred 298 K rate coefﬁcient is the average of the absolute and relative rate coefﬁcients of Sulbaek Andersen et al., 2004, Selleva˙ g et al. (2004) and Scollard et al. (1993). The rate coefﬁcient data of Dob ´ e ´ et al. (1989) was not used due to its large uncertainty. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4199 References Calvert, J. G., Atkinson, R., Kerr, J. A., Madronich, S., Moortgat, G. K., Wallington, T. J., and Yarwood, G.: The Mechanism of Atmospheric Oxidation of the Alkenes, Oxford University Press, New York, 2000. Dob ´ e, ´ S., Khachatryan, L. A. and Berces, T.: Ber. Bunsenges. Phys. Chem. 93, 847, 1989. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Balestra-Garcia, C., Laverdet, G., Le Bras, G., Mac Leod, H. and Teton, ´ S.: J. Phys. Chem. 97, 4683, 1993. Sellevag, ˚ S. R., Kelly, T., Sidebottom, H. and Nielsen, C. J.: Phys. Chem. Chem. Phys. 6, 1243, 2004. Sørensen, M., Kaiser, E. W., Hurley, M. D., Wallington, T. J. and Nielsen, O. J.: Int. J. Chem. Kinet. 35, 191, 2003. Sulbaek Andersen, M. P., Nielsen, O. J., Hurley, M. D., Ball, J. C., Wallington, T. J., Stevens, J. E., Martin, J. W., Ellis, D. A. and Mabury, S. A.: J. Phys. Chem. A., 108, 5189, 2004. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4200 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.31 HO + CF C(O)OH→ products Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (1.6± 0.4)× 10 315 Møgelberg et al., 1994 PR-RA −13 (1.5± 0.2)× 10 348 Relative Rate Coefﬁcients −19 2 3.73× 10 T exp[(375± 400)/T ] 283-323 Carr et al. 1994 RR (a,b) −13 (1.14± 0.10)× 10 298± 2 −13 (1.21± 0.22)× 10 298± 2 Carr et al., 1994 RR (a,c) −13 (1.75± 0.44)× 10 296 Møgelberg et al., 1994 RR (d) −14 (8.70± 1.44)× 10 296± 2 Hurley et al., 2004 RR (e,f) −13 (1.00± 0.11)× 10 296± 2 Hurley et al., 2004 RR (e,g) Comments (a) Relative rate method. HO radicals were generated by the 254 nm photolysis of O in the presence of water vapor in O - 3 3 H O-CF C(O)OH-C H (or C H )-O mixtures. The concentrations of CF C(O)OH and C H (or C H ) were measured 2 3 2 6 3 8 2 3 2 6 3 8 by FTIR spectroscopy. The measured rate coefﬁcient ratios of k(HO + CF C(O)OH)/k(HO + C H ) = 0.025 exp[(874 3 2 6 ± 400)/T ] (0.47 ± 0.04 at 298 ± 2 K) and k(HO + CF C(O)OH)/k(HO + C H ) = 0.11 ± 0.02 at 298 K, are placed 3 3 8 −17 2 3 −1 −1 on an absolute basis by using rate coefﬁcients of k(HO + C H ) = 1.5 × 10 T exp(-499/T ) cm molecule s 2 6 −12 3 −1 −1 (IUPAC, current recommendation) and k(HO + C H ) = 1.10 × 10 cm molecule s at 298 K (IUPAC, current 3 8 recommendation). (b) Relative to k(OH + ethane). (c) Relative to k(OH + propane). (d) Relative rate method. HO radicals were generated by the photolysis of O at 254 nm in the presence of H in O -H - 3 2 3 2 CF C(O)OH-C H -O mixtures at 740 Torr total pressure. The concentrations of CF C(O)OH and ethane were measured 3 2 6 2 3 by FTIR spectroscopy. The measured rate coefﬁcient ratio was k(HO + CF C(O)OH)/k(HO + C H ) = 0.59± 0.04. If the 3 2 6 (CF C(O)OH) dimer is unreactive towards the HO radical, then the rate coefﬁcient ratio corrected for dimer formation 3 2 is 0.84± 0.06. An average value of k(HO + CF C(O)OH)/k(HO + C H ) = 0.72± 0.18 was preferred and is placed on 3 2 6 −13 3 −1 −1 an absolute basis by using a rate coefﬁcient of k(HO + C H ) = 2.43 × 10 cm molecule s at 296 K (IUPAC, 2 6 current recommendation). (e) Relative rate method. HO radicals were generated by the photolysis of CH ONO in the presence of NO in air. CH ONO- 3 3 NO-CF C(O)OH-reference compound-air mixtures at 700 Torr total pressure were photolysed by UV lamps. Refer- ence compounds were C H and C H . The concentrations of CF C(O)OH, C H and C H were measured by FTIR 2 2 2 4 3 2 2 2 4 spectroscopy. The measure rate constant ratios of k(HO + CF C(O)OH)/k(HO + C H ) = 0.103 ± 0.017 and k(HO + 3 2 2 CF C(O)OH)/k(HO + C H ) = 0.0116 ± 0.0012 are placed on an absolute basis by using rate coefﬁcients of k(HO + 3 2 4 −13 3 −1 −1 −12 3 −1 C H ) = 8.45× 10 cm molecule s (Sørensen et al., 2003) and k(HO + C H ) = 8.66× 10 cm molecule 2 2 2 4 −1 s (Calvert et al. 2000), both at 296 K and 700 Torr of air. (f) Relative to k(HO + acetylene). (g) Relative to k(HO + ethene). Preferred Values −13 3 −1 −1 k = 1.3× 10 cm molecule s , independent of temperature over the range 280-350 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4201 Reliability 1 log k =± 0.1 over the temperature range 280-350 K. Comments on Preferred Values The preferred 298 K rate coefﬁcient is the average of the relative and absolute rate coefﬁcients of Møgelberg et al. (1994), Carr et al. (1994) and Hurley et al. (2004). The reaction is expected to proceed by overall H-atom abstraction from the -OH group to form H O + CF CO (see the data sheets on the HO radical reactions with HC(O)OH and CH C(O)OH). 2 3 2 3 References Calvert, J. G., Atkinson, R., Kerr, J. A., Madronich, S., Moortgat, G. K., Wallington, T. J., Yarwood, G.: The Mechanisms of Atmospheric Oxidation of the Alkenes, Oxford University Press, New York, 2000. Carr, S., Treacy, J. J., Sidebottom, H. W., Connell, R. K., Canosa-Mas, C. E., Wayne, R. P. and Franklin, J.: Chem. Phys. Lett. 227, 39, 1994. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Hurley, M. D., Sulbaek Andersen, M. P., Wallington, T. J., Ellis, D. A., Martin, J. W., and Mabury, S. A.: J. Phys. Chem. A. 615, 108, 2004. Møgelberg, T. E., Nielsen, O. J., Sehested, J., Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett. 226, 171, 1994. Sørensen, M., Kaiser, E. W., Hurley, M. D., Wallington, T. J., Nielsen, O. J.: Int. J. Chem. Kinet. 191, 35, 2003. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4202 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.32 HO + CH FO → O + CH FO H (1) 2 2 2 2 2 2 → O + HCOF + H O (2) 2 2 Rate coefﬁcient data(k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Branching Ratios k /k = 0.29± 0.08 295 Wallington et al., 1994 UVP-FTIR (a) k /k = 0.71± 0.11 295 Comments (a) HO and CH FO radicals were generated from the steady-state photolysis of Cl in the presence of CH F-H -air mixtures 2 2 2 2 3 2 at total pressures of 400–933 mbar. The branching ratios were derived from FTIR analysis of CH FO H and HCOF, which 2 2 accounted for 100± 13% of the loss of CH F. Preferred Values k /k = 0.3 at 298 K. k /k = 0.7 at 298 K. Reliability 1(k /k) = 1(k /k) =± 0.1 at 298 K. 1 2 Comments on Preferred Values The lack of a pressure dependence of the branching ratio determined by Wallington et al. (1994) indicates that there is no thermal decomposition of the products. The observation of two reaction channels for this reaction is in accord with data for other HO reactions with substituted peroxy radicals, for example, with HOCH O and CH OCH O radicals. 2 2 2 3 2 2 References Wallington, T. J., Hurley, M. D., Schneider, W. F., Sehested, J. and Nielsen, O. J.: Chem. Phys. Lett. 218, 34, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4203 IV.A1.33 HO + CF O → CF O H + O (1) 2 3 2 3 2 2 → C(O)F + HOF + O (2) 2 2 Rate coefﬁcient data(k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Branching Ratios −12 ≤ 2× 10 296 Hayman and Battin-Leclerc, 1995 FP-UVA (a) −12 (4.0± 2.0)× 10 295 Sehested et al., 1997 PR-UVA (b) −12 ≤ 3× 10 296 Biggs et al., 1997 DF-LIF (c) Comments (a) Flash photolysis of H O in the presence of CF CH F-O -N mixtures at a total pressure of 1013 mbar. Primary inves- 2 2 3 2 2 2 tigation of CF CHFO radical kinetics, with CF O radicals generated from the decomposition of product CF CHFO 3 2 3 2 3 radicals. Decays in transient absorption signals (with contributions from CF CHFO , HO and CF O ) were recorded in 3 2 2 3 2 the wavelength range 220 nm to 240 nm. Upper limit k derived from simulations of the decay traces using a 15 reaction mechanism. Good ﬁts could not be obtained if the CF O + HO was occurring appreciably under the experimental 3 2 2 conditions. (b) Pulse radiolysis study of CHF -H -O -SF mixtures at a total pressure of 1013 mbar. CF O and HO radicals were 3 2 2 6 3 2 2 monitored by UV absorption spectroscopy at 230 nm. Decays in transient absorption signals (with contributions from HO and CF O ) were recorded at 230 nm. The cited value of k was derived from simulation of the decay in absorption, 2 3 2 using a 13 reaction chemical mechanism. (c) Experiments performed at 2.7 mbar. CF O and HO radicals were produced by the F + CHF and F + CH OH reactions, 3 2 2 3 3 with subsequent addition of O . Both CF O and HO were monitored by titration to NO following reaction with excess 2 3 2 2 2 NO, with detection of NO by LIF. Upper limit k derived from simulations of the decay in radical concentration, using an −12 3 −1 −1 explicit reaction mechanism. Actual values obtained varied in the range < (1–3)× 10 cm molecule s . Preferred Values No recommendation Comments Although the results of Sehested et al. (1997) and Biggs et al. (1997) provide evidence for the occurrence of the reaction of HO with CF O , the rate coefﬁcient is not well-determined in any of the reported studies. No recommendation can be made 2 3 2 until further kinetics and product studies of this reaction are available. References Biggs, P., Canosa-Mas, C.E., Shallcross, D.E., Vipond, A. and Wayne, R.P.: J. Chem. Soc. Farad. Trans. 93, 2701, 1997. Hayman, G. and Battin-Leclerc, F.: J. Chem. Soc. Farad. Trans. 91, 1313, 1995. Sehested, J., Møgelberg, T., Fagerstrom, K., Mahmoud, G. and Wallington, T. J.: Int. J. Chem. Kinet. 29, 673, 1997. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4204 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.34 HO + CF CHFO → O + CF CHFO H (1) 2 3 2 2 3 2 → O + CF C(O)F + H O (2) 2 3 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 1.8× 10 exp[(910± 220)/T ] 210-363 Maricq et al., 1994 FP-UVA (a) −12 (4.7± 1.7)× 10 295 −12 (4.0± 2.0)× 10 296 Hayman and Battin-Leclerc, 1995 LP-UVA (b) −12 (3.3± 1.5)× 10 323 −12 (2.4± 1.5)× 10 373 −12 (5.0± 1.5)× 10 295 Sehested et al., 1997 PR-UVA (c) Branching Ratios k /k > 0.95 296 Maricq et al., 1994 UVP-FTIR (d) k /k < 0.05 296 Comments (a) Flash photolysis time-resolved UV absorption study of F -CF CH F-H -O -N mixtures. The rate coefﬁcients were 2 3 2 2 2 2 obtained from a ﬁt of the decay curves for CF CHFO , HO , CF O and ROOH, based on a mechanism of 14 reactions. 3 2 2 3 2 (b) Flash photolysis of H O in the presence of CF CH F-O -N mixtures at a total pressure of 1013 mbar. Decays in 2 2 3 2 2 2 transient absorption signals (with contributions from CF CHFO , HO and CF O ) were recorded in the wavelength 3 2 2 3 2 range 220 nm to 240 nm. k derived from simulations of the decay traces using a 15 reaction mechanism. (c) Pulse radiolysis study of CF CH F-H -O -SF mixtures at a total pressure of 1013 mbar. Decays in transient absorption 3 2 2 2 6 signals (with contributions from CF CHFO , HO and CF O ) were recorded at 230 nm and 240 nm. The cited value of 3 2 2 3 2 k was derived from simulation of the decay in absorption, using a 22 reaction chemical mechanism. (d) Steady-state photolysis of Cl -CF CH F-H -O -N mixtures with FTIR analysis of the products HC(O)F, CF C(O)F, 2 3 2 2 2 2 3 C(O)F and CF O CF . The branching ratio, k /k, cited above was based on measurements of CF COF, and the value of 2 3 3 3 2 3 k /k was inferred. Preferred Values −12 3 −1 −1 k = 4.3× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 2.0× 10 exp(910/T ) cm molecule s over the temperature range 210-365 K. k /k = 1.0 at 298. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. +0.0 1 (k /k) = at 298 K. −0.1 Comments on Preferred Values The preferred value of k at 298 K is the average of the results of Maricq et al. (1994) (based on their Arrhenius expression), Hayman and Battin-Leclerc (1995) and Sehested et al. (1997). The results of these studies are in good agreement, even though k Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4205 was necessarily extracted from simulations of complex systems. The preferred Arrhenius expression for k is based on the E/R value from the study of Maricq et al. (1994), combined with a pre-exponential factor adjusted to give the preferred value of k at 298 K. The results of Hayman and Battin-Leclerc (1995) at 323 K and 373 K are also consistent with this recommendation. The preferred branching ratios are based on those reported by Maricq et al. (1994), which require conﬁrmation. It is interesting to note that k is approximately a factor of two smaller than that recommended for the reaction of HO with C H O . This conﬁrms a deactivating inﬂuence of α-F and α-CF groups, observed for the reactions of a number of 2 5 2 3 halogenated peroxy radicals with HO . References Hayman, G. and Battin-Leclerc, F.: J. Chem. Soc. Faraday Trans. 91, 1313, 1995. Maricq, M. M., Szente, J. J., Hurley, M. D. and Wallington, T. J.: J. Phys. Chem. 98, 8962, 1994. Sehested, J., Møgelberg, T., Fagerstrom, K., Mahmoud, G. and Wallington, T. J.: Int. J. Chem. Kinet. 29, 673, 1997. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4206 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.35 HO + CF CF O → O + CF CF O H (1) 2 3 2 2 2 3 2 2 → O + CF C(O)F + HOF (2) 2 3 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (1.2± 0.6)× 10 296 Hayman and Battin-Leclerc, 1995 LP-UVA (a) Comments (a) Flash photolysis of H O in the presence of CF CHF -O -N mixtures at a total pressure of 1013 mbar. Decays in 2 2 3 2 2 2 transient absorption signals (with contributions from CF CF O , HO and CF O ) were recorded in the wavelength 3 2 2 2 3 2 range 220 nm and 230 nm. k derived from simulations of the decay traces using a 16 reaction mechanism. Preferred Values −12 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.5 at 298 K. Comments on Preferred Values While the above value of the rate coefﬁcient seems reasonable, it has been derived from the analysis of a complex chemical system and requires independent veriﬁcation to reduce the recommended error limits. It is interesting to note that k is substan- tially smaller than that recommended for the reaction of HO with C H O . This conﬁrms a deactivating inﬂuence of α-F and 2 2 5 2 α-CF groups, observed for the reactions of a number of halogenated peroxy radicals with HO . 3 2 References Hayman, G. and Battin-Leclerc, F.: J. Chem. Soc. Faraday Trans. 91, 1313, 1995. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4207 IV.A1.36 FO + CO→ products Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −16 < 5.1× 10 298 Sehested et al., 1994 PR-UVA (a) Comments (a) Pulse radiolysis of CO-O -SF mixtures in a high pressure cell at 18 bar SF . The decay of FO radicals was monitored 2 6 6 2 in absorption at 220 nm. Preferred Values −16 3 −1 −1 k < 6× 10 cm molecule s at 298 K. Comments on Preferred Values The preferred room temperature upper limit is based on results of the pulse radiolysis-UV absorption study of Sehested et al. (1994). This is the sole reported study of this reaction. References Sehested, J., Sehested, K., Nielsen, O. J. and Wallington, T. J.: J. Phys. Chem. 98, 6731, 1994. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4208 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.37 FO + CH → products 2 4 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 < 4× 10 298 Sehested et al., 1994 (a) Comments (a) Pulse radiolysis/UV absorption spectroscopy technique. Pulse radiolysis of CH -O -SF mixtures in a high pressure cell 4 2 6 at 18 bar SF . The decay of FO radicals was monitored in absorption at 220 nm. 6 2 Preferred Values −15 3 −1 −1 k < 4.1× 10 cm molecule s at 298 K. Comments on Preferred Values The preferred room temperature upper limit is based on results of the pulse radiolysis-UV absorption study of Sehested et al. (1994). This is the sole reported study of this reaction rate coefﬁcient. References Sehested, J., Sehested, K., Nielsen, O. J. and Wallington, T. J.: J. Phys. Chem. 98, 6731, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4209 IV.A1.38 CF + O + M→ CF O + M 3 2 3 2 ◦ −1 1H (1) = -148 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −29 (2.0± 0.1)× 10 [He] 295 Ryan and Plumb, 1982 DF-MS (a) −29 −4.7 (1.9± 0.2)× 10 (T /300) [N ] 233-373 Caralp et al., 1986 PLP-MS (b) −29 (2.5± 0.3)× 10 [N ] 295 Breheny et al., 2001 PLP-CL (c) Comments (a) Microwave discharge-ﬂow system coupled to quadrupole MS. CF radicals monitored by MS. Measurements over the −12 3 −1 −1 range 0.7–11 mbar, extrapolated with F ≈ 0.4 and k ≈ 8.0× 10 cm molecule s . c ∞ −12 3 (b) Pulsed laser photolysis-MS study over the range 0.3–16 mbar. Extrapolation with F ≈ 0.6 and k ≈ 9.0 × 10 cm c ∞ −1 −1 molecule s . (c) Pulsed laser photolysis-IR chemiluminescence study of CF I in the presence of NO and O , using IR emission from the 3 2 2 −12 reaction CF + NO for detection. Pressure range 2.7–150 mbar. Extrapolation with F ≈ 0.6 and k ≈ 2.55 × 10 3 2 c ∞ 3 −1 −1 cm molecule s , using data up to 800 mbar from relative rate measurements by Kaiser et al. (1995). Preferred Values −29 −4.7 3 −1 −1 k = 2.2× 10 (T /300) [N ] cm molecule s over the temperature range 230–380 K. 0 2 Reliability 1 log k =± 0.1 at 298 K. 1 n =± 1.5. Comments on Preferred Values The preferred values are an average of the low pressure results from Caralp et al. (1986), and Breheny et al. (2001) which appear well consistent with the measurements in He from Ryan and Plumb (1982). Differences in k and F , used in the ∞ c extrapolation, only slightly inﬂuence the preferred k because all measurements extended to pressures close to the low pressure limit of k. High-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 1.0× 10 298 Cooper et al., 1980 PR (a) Relative Rate Coefﬁcients −12 (3.92± 0.25)× 10 271-363 Kaiser et al., 1995 PR (b) www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4210 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments (a) Pulse radiolysis of CF Cl. CF O detected by UV absorption spectroscopy near 260 nm. Measurements in 920 mbar of 3 3 2 Ar. (b) UV irradiation of CF I-CH -Cl -N -O mixtures and observation of loss of CF and CH . Measurement of the ratio 3 4 2 2 2 3 4 k(CF + O )/k(CF + Cl ) as a function of the pressure and calibration of this ratio at low pressures against k (CF + O ) 3 2 3 2 0 3 2 from Caralp et al. (1986). Inspection of the spectra recorded by Cooper et al. (1980) and comparison with more recently detected spectra of CF O indicates that the rate of CF + O was not observed by Cooper et al. (1980). 3 2 3 2 Preferred Values −12 3 −1 −1 k = 4× 10 cm molecule s over the temperature range 200-300 K. Reliability 1 log k =± 0.3 at 298 K. 1 n =± 1.5. Comments on Preferred Values Since the measurements of Cooper et al. (1980) were shown not to lead to k , the results from the relative rate measurements from Kaiser et al. (1995) are preferred. They are similar as values for k for CCl + O from Luther et al. (2001) for which ∞ 3 2 n = -1.4 was measured. Using an estimated F = 0.39 independent of the temperature, all results (except those from Cooper et al. (1980)) are consistently represented and the remaining uncertainty of k does not impact on k . ∞ 0 References Breheny, C., Hancock, G. and Morrell, C.: Z. Phys. Chem., 215, 305, 2001. Caralp, F., Lesclaux, R. and Dognon, A. M.: Chem. Phys. Lett., 129, 433, 1986. Cooper, R., Cumming, J. B., Gordon, S. and Mulac, W. A.: Rad. Phys. Chem., 16, 169, 1980. Kaiser, E. W., Wallington, T. J. and Hurley, M. D.: Int. J. Chem. Kinet., 27, 205, 1995. Luther, K., Oum, K. and Troe, J.: J. Phys. Chem. A, 105, 5535, 2001. Ryan, K. R. and Plumb, I. C.: J. Phys. Chem., 86, 4678, 1982. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4211 IV.A1.39 CF O + O → COF + FO 3 2 2 2 ◦ −1 1H (1) = 47.0 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −17 <2× 10 298 Turnipseed et al., 1994 PLP/LIF (a) −17 <4× 10 373 Comments (a) CF O radicals were generated by photolysis of CF OOCF at 193 nm. 3 3 3 Preferred Values −18 3 −1 −1 k < 1× 10 cm molecule s at 298 K. −10 3 −1 −1 k < 1× 10 exp(-5600/T ) cm molecule s over the temperature range 250-370 K. Comments on Preferred Values The preferred values are based on the upper limit at 373 K reported by Turnipseed et al. (1994). Assuming that the activation energy barrier is at least equal to the reaction endothermicity (5600 K) leads to the preferred limits given for the A-factor and for k(298 K). This procedure using the high temperature limit yields a room temperature limit an order of magnitude lower than the upper limit to the rate coefﬁcient directly determined at 298 K. Chen et al. (1992) in a long path FTIR study of the reaction of CF O with NO found no evidence for the reaction of CF O with O in 1 bar of air at room temperature. 3 3 2 References Chen, J., Zhu, T. and Niki, H.: J. Phys. Chem., 96, 6115, 1992. Turnipseed, A. A., Barone, S. B. and Ravishankara, A. R.: J. Phys. Chem., 98, 4594, 1994. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4212 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.40 CF O + O → CF O + O 3 3 3 2 2 ◦ −1 1H (1) = -101.1 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 <1× 10 295 Nielsen and Sehested, 1993 PR/UVA (a) −14 <5× 10 210-353 Maricq and Szente, 1993 FP/UVA (b) −15 <2× 10 298 Fockenberg et al., 1994 LP/LIF (c) −14 <4× 10 298 Ravishankara et al., 1994 FT/CIMS (d) −14 (2.5± 0.7)× 10 298 Turnipseed et al., 1994 PLP/LIF (e) −14 (3.7± 1.5)× 10 373 −15 (2.8± 0.5)× 10 298 Meller and Moortgat, 1995 (f) −14 (1.3± 0.5)× 10 298 Bourbon et al., 1996 FT/LIF (g) Relative Rate Coefﬁcients −14 <3× 10 295 Wallington et al., 1993 RR (h) −14 (1.5± 0.5)× 10 296 Wallington and Ball, 1995 (i) Comments (a) Radicals generated by pulse radiolysis of CHF -O -O -SF mixtures. Upper limit for k derived from simulations of ozone 3 2 3 6 absorption transients at 254 nm and 276 nm in the presence of CF O and CF O radicals. 3 3 2 (b) Radicals generated by 351 nm photolysis of F in a ﬂowing F -CHF -O -O -N mixture. O and CF O radicals were 2 2 3 3 2 2 3 3 2 monitored by absorption at 255 nm and 210 nm respectively. (c) CF O radicals were generated by excimer laser photolysis of CF OCl at 351 nm. 3 3 (d) CF O radicals were generated by pyrolysis of CF OOCF . 3 3 3 (e) CF O radicals were generated by photolysis of CF OOCF at 193 nm. 3 3 3 (f) Static photolysis of CF OOCF in the presence of O ; Analysis of CF O and CF OO CF products by FTIR. k deter- 3 3 3 3 3 3 3 mined by analysis of complex mechanism. (g) CF O radicals were generated by pyrolysis of CF OOCF . 3 3 3 (h) Radicals generated by visible photolysis of CF NO/O mixtures in 700 torr O . Analysis was by FTIR spectrometer. 3 3 2 Value of k was derived by authors from the measured ratio k/k(CF O + NO ) and an estimated value of k(CF O + NO ). 3 2 3 2 −14 3 −1 −1 (i) Relative rate technique using FTIR. k measured relative to k(CF O + CH ) = 2.2× 10 cm molecule s at 298 K 3 4 (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 1.8× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2× 10 exp(-1400/T ) cm molecule s over the temperature range 250–370 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4213 Reliability 1 log k =± 1 at 298 K. 1 (E/R) =± 600 K. Comments on Preferred Values The preferred value of k at 298 K is an average of the room temperature results of Turnipseed et al. (1994), Wallington and Ball (1995) and Bourbon et al (1996). Fockenberg et al. (1994) and Meller and Moortgat (1995) reported room temperature values an order of magnitude lower. The reason for this discrepancy is unknown, although both studies appear to have possibilities for interference by secondary chemistry. Upper limits reported in the studies of Nielsen and Sehested (1993), Maricq and Szente (1993), Ravishankara et al. (1994) and Wallington et al. (1993) are all consistent with the recommendation. Because of the large uncertainties in the two values of Turnipseed et al. (1994), Arrhenius parameters have not been derived using these values. Rather, the recommended A factor has been estimated by analogy with other CF O reactions, and the value of E/R ﬁtted to the preferred room temperature value. References Bourbon, C., Brioulov, M. and Devolder, P.: C. A. Acad. Sci..Paris, 322, 181, 1996. Fockenberg, C., Saathoff, H. and Zellner, R.: Chem. Phys. Lett., 218, 21, 1994. Maricq, M. M. and Szente, J. J.: Chem. Phys. Lett., 213, 449, 1993. Meller, R. and Moortgat, G. K.: J. Photochem. Photobiol. A: Chem., 86, 15, 1995. Nielsen, O. J. and Sehested, J.: Chem. Phys. Lett., 213, 433, 1993. Ravishankara, A. R., Turnipseed, A. A., Jensen, N. R., Barone, S., Mills, M., Howard, C. J. and Solomon, S.: Science, 263, 71, 1994. Turnipseed, A. A., Barone, S. B. and Ravishankara, A. R.: J. Phys. Chem., 98, 4594, 1994. Wallington, T. J. and Ball, J. C.: Chem. Phys. Lett., 234, 187, 1995. Wallington, T. J., Hurley, M. D. and Schneider, W. F.: Chem. Phys. Lett., 213, 442, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4214 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.41 CF O + H O→ CF OH + HO 3 2 3 ◦ −1 1H (1) = 43.4 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −16 <1× 10 298 Turnipseed et al., 1995 (a) −16 <2× 10 381 Relative Rate Coefﬁcients −18 >2× 10 296 Wallington et al., 1993 (b) −16 <4× 10 296 Comments (a) Pulsed laser photolysis/pulsed laser induced ﬂuorescence technique. CF O radicals were generated by photolysis of CF OOCF at 193 nm. 3 3 (b) Long path FTIR-based study. CF O radicals generated by chlorine-initiated oxidation of CF CFH (HFC-134a) in pho- 3 3 2 tolytic mixture of Cl -CF CFH -H O in 1 bar air. Reaction rate studied in competition with the rate of CF O + CF CFH . 2 3 2 2 3 3 2 Preferred Values −17 3 −1 −1 k < 2× 10 cm molecule s at 298 K. −12 3 −1 −1 k < 3× 10 exp(-3600/T ) cm molecule s over the temperature range 250-380 K. Comments on Preferred Values The A-factor is estimated by analogy with similar reactions of CF O and the activation energy is ﬁtted to the upper limit at 381 K reported by Turnipseed et al. (1995). Note that this procedure results in a lower limit for E/R (E/R > 3600 K). The preferred value of k(298 K) is calculated from the Arrhenius parameters. The limits reported by Wallington et al. (1993) are consistent with this preferred value. References Turnipseed, A. A., Barone, S. B., Jensen, N. R., Hanson, D. R., Howard, C. J. and Ravishankara, A. R.: J. Phys. Chem., 99, 6000 , 1995. Wallington, T. J., Hurley, M. D., Schneider, W. F., Sehested, J. and Nielsen, O. J.: J Phys. Chem., 97, 7606, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4215 IV.A1.42 CF O + NO→ COF + FNO 3 2 ◦ −1 1H = -135 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 (5.2± 2.7)× 10 295 Sehested and Nielsen, 1993 PR/UVA (a) −11 3.34× 10 exp[(160± 45)/T ] 233-360 Turnipseed et al., 1994 PLP/LIF (b) −11 (5.62± 0.74)× 10 298 −11 4.1× 10 exp[(60± 100)/T ] 231-393 Jensen et al., 1994 (c) −11 (5.0± 1.0)× 10 298 −11 (4.7± 0.9)× 10 298 Bourbon et al., 1996 DF/LIF (d) −11 (4.72± 0.30)× 10 293 Bhatnagar and Carr, 1994 FP/MS (e) −11 4.1× 10 exp[(60± 100)/T ] 213-253 Dibble et al., 1995 LP/TDLS (f) Comments (a) Radicals generated by pulse radiolysis of CHF -O -NO-SF mixtures. Value of k derived from simulations of FNO 3 2 6 absorption transients at 310.5 nm. (b) CF O radicals were generated by photolysis of CF OOCF at 193 nm. 3 3 3 (c) Flow tube reactor/chemical ionization mass spectrometer technique. CF O radicals were generated by pyrolysis of CF OOCF . A low value of k from the same laboratory reported earlier by Bevilacqua et al. (1993) is superseded 3 3 by these results. (d) CF O radicals were generated by DF technique in F/CF H/O /NO system. 3 3 2 (e) k obtained by modeling NO time dependence during secondary reactions in CF O + NO reaction. 3 2 (f) CF O radicals were generated by photolysis of CF OOCF at 193 nm. Time resolved formation of COF using tunable 3 3 3 2 −1 diode laser absorption near 1950 cm . FNO identiﬁed as major co-product with COF . Preferred Values −11 3 −1 −1 k = 5.4× 10 cm molecule s at 298 K. −11 3 −1 −1 k = 3.7× 10 exp(110/T ) cm molecule s over the temperature range 230-390 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 100 K. Comments on Preferred Values The preferred values are based on the 233–360 K values of Turnipseed et al. (1994), the 231–393 K values of Jensen et al. (1994) and the 295 K value of Sehested and Nielsen (1993). These results are in good agreement. The low value of k reported by Bevilacqua et al. (1993) has been superseded by the results of Jensen et al. (1994). Room temperature results from Bourbon et al. (1996) and Bhatnagar and Carr (1994) and a temperature dependence study of Dibble et al (1995) are in good agreement with the recommendation. The reaction products have been reported by Chen et al. (1992), Bevilacqua et al. (1993) and Li and Francisco (1991). www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4216 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Bevilacqua, T. J., Hanson, D. R. and Howard, C. J.: J. Phys. Chem., 97, 3750, 1993. Bhatagar, A. and Carr, R.W.: Chem. Phys. Lett., 231, 454, 1994. Bourbon, C., Briuokov, M., Hanoune, B., Sawersyn, J. P. and Devolder, P.: Chem. Phys. Lett., 254, 203, 1996. Chen, J., Zhu, T. and Niki, H.: J. Phys. Chem. 96, 6115, 1992. Dibble, T. S., Maricq, M. M., Szente, J. J. and Francisco, J. S.: J. Phys. Chem., 99, 17394, 1995. Jensen, N. R., Hanson, D. R. and Howard, C. J.: J. Phys. Chem., 98, 8574, 1994. Li, Z. and Francisco, J. S.: Chem. Phys. Lett., 186, 336 , 1991. Sehested, J. and Nielsen, O. J.: Chem. Phys. Lett., 206, 369, 1993. Turnipseed, A. A., Barone, S. B. and Ravishankara, A. R.: J. Phys. Chem., 98, 4594, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4217 IV.A1.43 CF O + CH → CF OH + CH 3 4 3 3 ◦ −1 1H (1) = -16.9 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (2.2± 0.2)× 10 298 Saathoff and Zellner, 1993 LP/LIF (a) −12 1.92× 10 exp[-(1370± 85)/T ] 247-360 Barone et al., 1994 PLP/LIF (b) −14 (1.93± 0.11)× 10 298 −12 3.1× 10 exp[-(1470± 250)/T ] 231-385 Jensen et al., 1994 DF/CIMS (c) −14 (2.2± 0.4)× 10 298 −12 4.49× 10 exp[-(1606± 84)/T ] 296-573 Bourbon et al., 1995 DF/LIF (d) −12 (2.05± 0.20)× 10 298 −12 3.3× 10 exp[-(1430± 150)/T ] 235-401 Bednarek et al., 1995 LP/LIF (e) −14 2.5× 10 298 Relative Rate Coefﬁcients −15 <5× 10 297 Chen et al., 1992 (f) −14 (1.2± 0.1)× 10 298 Kelly et al., 1993 (g) Comments (a) CF O radicals were generated by photolysis of CF OF at 248 nm. 3 3 (b) CF O radicals were generated by photolysis of CF OOCF at 193 nm. 3 3 3 (c) CF O radicals were generated by pyrolysis of CF OOCF . 3 3 3 (d) CF O radicals were generated by the pyrolysis of CF OOCF . 3 3 3 (e) CF O radicals were generated by photolysis of CF OF at 248 nm. 3 3 (f) Long path FTIR-based product study of visible photolysis of CF NO-NO-CH mixtures in 700 torr air. Searched for 3 4 CH O product from oxidation of CH initiated by reaction of CF O radicals with CH . Upper limit of k given in table is 2 4 3 4 −4 derived from the measured ratio k/k(CF O+NO) <10 and the value of k(CF O+NO) given in this evaluation. 3 3 (g) Long-path FTIR-based study. CF O radicals were generated by photolysis of CF OOCF . The decay of the reactant 3 3 3 hydrocarbon was compared with the decay of the reference hydrocarbon. The value of k given in table is derived from the measured ratio k/k(CF O + C H ) = 0.010± 0.001 and the value of k(CF O+C H ) (IUPAC, current evaluation). 3 2 6 3 2 6 Preferred Values −14 3 −1 −1 k = 2.2× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.6× 10 exp(-1420/T ) cm molecule s over the temperature range 230-380 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 200 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4218 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The preferred value at room temperature is the average of the values reported by Saathoff and Zellner (1993), Barone et al. (1994), Jensen et al. (1994), Bourbon et al. (1995) and Bednarek et al. (1994). Results of these direct studies are in excellent agreement at room temperature. The temperature dependence is based on the 247–360 K data of Barone et al. (1994), the 231–385 K data of Jensen et al. (1994) and the 235–401 K data of Bednarek et al. (1994). The temperature dependence of Bourbon et al. (1995) is thought to be high due to possible inﬂuence of wall reaction at high temperature. The relative rate measurements of Chen et al. (1992) and Kelly et al. (1993) are factors of 4 and 2, respectively, lower than the preferred value. Wallington and Ball (1995) reported k/k(CF O + C H ) = 0.0152 ± 0.0023 at 296 K in good agreement with the 3 2 6 recommended rate coefﬁcients. Jensen et al. (1994) detected the product CF OH by chemical ionization mass spectrometer (CIMS) and observed its formation to correlate with the loss of the CF O reactant. The CF OH product of this reaction was 3 3 also observed by Bevilacqua et al. (1993) and also by Bednareck et al. (1994), who used FTIR spectroscopy to show that CF OH is converted slowly to C(O)F . 3 2 References Barone, S. B., Turnipseed, A. A. and Ravishankara, A. R.: J. Phys. Chem., 98, 4602, 1994. Bednarek, G., Kohlmann, J. P., Saathoff, H. and Zellner, R.: Z. Phys. Chem., 188, 1, 1995. Bevilacqua, T. J., Hanson, D. R. and Howard, C. J.: J. Phys. Chem. 97, 3750, 1993. Bourbon, C., Fittschen, C., Sawersyn, J. P. and Devolder, P.: J. Phys. Chem., 99, 15102, 1995. Chen, J., Zhu, T., Niki, H. and Mains, G. J.: Geophys. Res. Lett., 19, 2215, 1992. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jensen, N. R., Hanson, D. R. and Howard, C. J.: J. Phys. Chem., 98, 8574, 1994. Kelly, C., Treacy, J., Sidebottom, H. W. and Nielsen, O. J.: Chem. Phys. Lett., 207, 498, 1993. Saathoff, H. and Zellner, R.: Chem. Phys. Lett., 206, 349, 1993. Wallington, T. J. and Ball, J. C.: J. Phys. Chem., 99, 3201, 1995. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4219 IV.A1.44 CF O + C H → CF OH + C H 3 2 6 3 2 5 ◦ −1 1H (1) = -32.2 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (1.2± 0.2)× 10 298 Saathoff and Zellner, 1993 (a) −12 4.84× 10 exp[-(400± 70)/T ] 233-360 Barone et al., 1994 (b) −12 (1.30± 0.11)× 10 298 −11 1.13× 10 exp[-(642± 113)/T ] 295-573 Bourbon et al., 1995 (c) −12 (1.31± 0.13)× 10 298 Relative Rate Coefﬁcients −12 (1.1± 0.6)× 10 297 Chen et al., 1992 (d) Comments (a) Laser photolysis/laser induced ﬂuorescence technique. CF O radicals were generated by the photolysis of CF OF at 248 3 3 nm. (b) Pulsed laser photolysis/pulsed laser induced ﬂuorescence technique. CF O radicals were generated by the photolysis of CF OOCF at 193 nm. 3 3 (c) Fast ﬂow tube (∼1.3 mb pressure)/laser induced ﬂuorescence. CF O radicals were generated by the pyrolysis of CF OOCF at 193 nm. 3 3 (d) Long path FTIR-based product study of visible photolysis of CF NO-NO-C H mixtures in 700 Torr air. The upper limit 3 2 6 of k given in table is derived from measured ratio k/k(CF O+NO) = 0.02± 0.006 and the value of k(CF O+NO) (IUPAC, 3 3 current recommendation). Preferred Values −12 3 −1 −1 k = 1.3× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 4.9× 10 exp(-400/T ) cm molecule s over the temperature range 230-360 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The preferred value at room temperature is the average of the values reported by Saathoff and Zellner (1993), Barone et al. (1994) and Bourbon et al. (1995). Results of these direct studies are in excellent agreement. The temperature dependence is based on the 233–360 K data of Barone et al. (1994). The temperature dependence of Bourbon et al. (1995) is thought to be high due to possible inﬂuence of wall reaction at high temperature. The relative rate measurement of Chen et al. (1992) is in good agreement with the preferred value. Kelly et al. (1993) used a relative rate method with FTIR detection to determine the rate of CF O reaction with a number of hydrocarbons relative to the rate of the reaction of CF O with C H . They reported 3 3 2 6 k(CF O + CH )/k = 0.010± 0.001 at 298 K and 1 bar pressure (Kelly et al., 1993). This is nearly a factor of 2 lower than the 3 4 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4220 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry ratio of the preferred values given in this evaluation (0.017). Wallington and Ball (1995) reported k(CF O + CH )/k = 0.0152 3 4 ± 0.0023 at 296 K in good agreement with the recommended rate coefﬁcients. References Barone, S. B., Turnipseed, A. A. and Ravishankara, A. R.: J. Phys. Chem., 98, 4602, 1994. Bourbon, C., Fittschen, C., Sawersyn, J. P. and Devolder, P.: J.Phys.Chem., 99, 15102, 1995. Chen, J., Zhu, T., Niki, H. and Mains, G. J.: Geophys. Res. Lett., 19, 2215, 1992. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Kelly, C., Treacy, J., Sidebottom, H. W. and Nielsen, O. J.: Chem. Phys. Lett., 207, 498, 1993. Saathoff, H. and Zellner, R.: Chem. Phys. Lett., 206, 349, 1993. Wallington, T. J. and Ball, J. C.: J. Phys.Chem., 99, 3201, 1995. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4221 IV.A1.45-54 R (R )CHO + O → R COR + HO (or→ products) (1) 1 2 2 1 2 2 R (R )CHO (+ M)→ products (2) 1 2 R = alkyl, halogenated alkyl, H or halogen atom Rate coefﬁcient data 3 −1 Reaction Reactions k /k cm molecule Temp./K Reference Comments 1 2 Number IV.A1.45 CH FO + O → HCOF + HO (1) k [O ] k (933 mbar, air) 298 Edney and Driscoll, 1992 (a) 2 2 2 1 2 2 IV.A1.46 CH FO + M→ HCOF + H + M (2) k [O ] k (986 mbar, air) 298 Tuazon and Atkinson, 1993a (a) 2 1 2 2 IV.A1.47 CH CF O + O → products (1) k [O ] k (933 mbar, air) 298 Edney and Driscoll, 1992 (b) 3 2 2 1 2 2 IV.A1.48 CH CF O + M→ CH + COF + M (2) k [O ] k (986 mbar, air) 298 Tuazon and Atkinson, 1993a (c) 3 2 3 2 1 2 2 IV.A1.49 CH FCHFO + O → CH FCOF + HO (1) k [O ] k (933 mbar, air) 296 Wallington et al., 1994 (d) 2 2 2 2 1 2 2 IV.A1.50 CH FCHFO + M→ CH F+ HCOF + M (2) 2 2 −25 IV.A1.51 CF CHFO + O → CF COF + HO (1) 1.58× 10 exp(3600/T ) 296 Wallington et al., 1992 (e) 3 2 3 2 −20 IV.A1.52 CF CHFO + M→ CF + HCOF (2) 2.8× 10 (2 bar) 298 3 3 −25 3.2× 10 exp(3510/T ) 273-320 Tuazon and Atkinson, 1993b (f) −20 4.5× 10 (986 mbar) 298 7 −1 k = 3.7× 10 exp(-2200/T )s 211-372 Maricq and Szente, 1992 (g) 4 −1 k = 2.3× 10 s (307 mbar) 298 −24 1.18× 10 exp(2860/T ) 235-318 Rattigan et al., 1994 (h) −20 1.7× 10 (1 bar) 298 −19 1.5× 10 (50 mbar) 295 Bednarek et al, 1996 (i) −15 k = 2.7× 10 295 −25 8.7× 10 exp(3240/T ) (1 bar) 244-295 −25 2.1× 10 exp(3625/T ) (1 bar) 238-295 Wallington et al, 1996 (j) −24 3.8× 10 exp(2400/T ) (1 bar) 298-357 Hasson et al, 1998 (k) IV.A1.53 CF CF O + O → products (1) k [O ] k (933 mbar, air) 298 Edney and Driscoll, 1992 (l) 3 2 2 1 2 2 IV.A1.54 CF CF O + M→ CF + CF O + M (2) k [O ] k (986 mbar, air) 298 Tuazon and Atkinson, 1993a (m) 3 2 3 2 1 2 2 Comments (a) Steady-state photolysis of Cl in the presence of CH F-air mixtures (1 atm) with FTIR absorption spectroscopic analysis: 2 3 a 100% yield of HCOF was observed, consistent with k [O ] k . 1 2 2 (b) Steady-state photolysis of Cl in the presence of CH CHF -air mixtures (1 atm) with FTIR absorption spectroscopic 2 3 2 analysis: a 100± 5% yield of COF was observed, consistent with k [O ] k . 2 1 2 2 (c) Similar experiments to those of Comment (b); a 92.2 ± 1.2 % yield of COF , plus other unidentiﬁed products, was observed, consistent with k [O ] k . 1 2 2 (d) Steady-state photolysis of Cl in the presence of CH FCH F-air mixtures (933 mbar) with FTIR analysis: a 91± 10% 2 2 2 yield of HCOF was observed, consistent with k [O ] k . 1 2 2 (e) Steady-state photolysis of Cl in the presence of CF CFH -O -N mixtures at total pressures of 2 atm with FTIR analysis 2 3 2 2 2 of products CF COF and HCOF. The ratio k /k was found to be pressure dependent over the range 27–732 mbar but 3 1 2 approximately independent of pressure above 933 mbar. (f) Similar experiments to those of Comment (e) at a total pressure of 986 mbar. (g) Flash-photolysis time-resolved UV absorption spectroscopic study of CF CHFO radicals from F -CF CH F-O -N 3 2 2 3 2 2 2 mixtures, k obtained from a ﬁt of CF O formation proﬁles, produced from reaction (1) followed by CF + O + M. 1 3 2 3 2 Experiments were carried out at a total pressure of 306 mbar, well below the high-pressure limit. (h) Cl - initiated photooxidation of CF CH F at 1atm pressure, with dual-beam diode-array UV spectroscopic determination 2 3 2 of CF COF and HCOF products. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4222 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry (i) Direct time-resolved experiment using laser pulsed photolysis-laser long path absorption; CF CFHO produced by CF CFHO + NO reaction and kinetics of thermal decomposition reaction determined at p = 50 mbar and 295 K. The 3 2 relatve rate ratio cited for k /k was determined in a second experiment carried out over the temperature range 244–295 1 2 K and p = 1 bar, using UV photolysis and FTIR analysis of products. (j) Steady-state photolysis of Cl in the presence of CF CFH -O -N mixtures at total pressures of 55–800 mbar with FTIR 2 3 2 2 2 analysis of products CF COF and HCOF. Experiments also carried out with NO present so that CF CFHO was produced 3 3 by CF CFHO + NO reaction, as opposed to the self reaction of CF CFHO . The ratio k /k was found to increase 3 2 3 2 1 2 with pressure over the range given but approximately independent of pressure above 1500 mbar. The ratio k /k was 1 2 signiﬁcantly lower in the NO experiments. This was ascribed to the production of vibrationally hot CF CFHO radicals which decompose promptly to CF + HCFO, in the more exothermic source reaction. (k) Steady-state photolysis of F in the presence of CF CFH -O -N mixtures (p = 910 mbar) with FTIR absorption spectro- 2 3 2 2 2 scopic analysis. (l) Steady-state photolysis of Cl in the presence of CF CHF -air mixtures (1 atm) with FTIR absorption spectroscopic 2 3 2 analysis; a 109± 5% yield of C(O)F was observed, consistent with k [O ] k . 2 1 2 2 (m) Similar experiments to those in Comment (l) at a total pressure of 986 mbar; a ∼ 100% yield of C(O)F was observed consistent with k [O ] k . 1 2 2 Preferred Values R (R )CHO = CF CHFO 1 2 3 −20 3 −1 k /k = 4.0× 10 cm molecule at 298 K and 1 bar pressure. 1 2 −25 3 −1 k /k = 2.1× 10 exp(3625/T ) (1bar) cm molecule over the temperature range 260-355 K. 1 2 1 (E/R) =± 500 K. Comments on Preferred Values R (R )CHO = CF CHFO 1 2 3 The recommended temperature dependence rate coefﬁcient ratio is that evaluated by Wallington et al. (1996) from their own data together with those of Wallington et al. (1992), Tuazon and Atkinson (1993b), Meller et al. (1994) and Benarek et al. (1996). The data were corrected for a small pressure dependence measured by Wallington at al. (1996) at 298 K and the expression refers to reactions of the thermalised CF CHFO radicals. This study also revealed that energy rich CF CHFO 3 3 radicals were formed when the radical was produced from the CF CHFO + NO reaction, leading to formation of HC(O)F by 3 2 prompt decomposition at atmospheric temperatures, reducing the relative rate of O reaction by a factor of 1.8–4.0. Several theoretical studies have investigated the decomposition of CF CHFO radicals and have conﬁrmed that this interpretation is realistic. (Schneider et al., 1998; Somnitz and Zellner, 2001). R (R )CHO = other radicals in the above table. 1 2 For the purpose of atmospheric modeling studies it is recommended that the above qualitative information on the ratios k /k be 1 2 used to decide if one or other of the alkoxy radical reaction pathways predominates or if both pathways should be considered. References Bednarek, G., Breil, M., Hoffmann, A., Kohlmann, J. P., Mrs, V., and Zellner, R.: Ber. Bunsenges. Phys. Chem. 100, 528, Edney, E. O. and Driscoll, D. J.: Int . J. Chem. Kinet. 24, 1067, 1992. Hasson, A. S., Moore, C. M. and Smith I. W. M.: Int. J. Chem. Kinet. 30, 541, 1998. Maricq, M. M., Shi, J., Szente, J. J., Rimai, L. and Kaiser, E. W.: J. Phys. Chem. 97, 9686, 1993. Meller, R., Boghu, D. and Moortgat, G. K.: EUR 16171 EN, Becker, K. H. (ed), Tropospheric Oxidation Mechanisms, Joint EC/EuroTrac/GDCU Workshop, LACTOZ-HALIPP, Leipzig, September 20-22, 1994. Rattigan , O. V., Rowley, D. M., Wild, O., Jones, R. L. and Cox, R. A.: J. Chem. Soc. Faraday Trans. 90, 1819, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4223 Schneider, W. F., Wallington, T. J., Barker, J. R. and Stahlberg, E. A.: Ber. Bunsenges. Phys. Chem. 102, 1850, 1998. Somnitz, H. and Zellner, R.: Phys. Chem. Chem. Phys. 3, 2352, 2001. Tuazon, E. C. and Atkinson, R.: J. Atmos. Chem. 16, 301, 1993b. Tuazon, E. C. and Atkinson, R.: J. Atmos. Chem. 17, 179, 1993a. Wallington, T. J., Hurley, M. D., Ball, J. C. and Kaiser, E. W.: Environ.Sci. Technol. 26, 1318, 1992. Wallington, T. J., Hurley, M. D., Ball, J. C., Ellermann, T., Nielsen, O. J. and Sehested, J.: J. Phys. Chem. 98, 5435, 1994. Wallington, T. J., Hurley, M. D., Fracheboud, J. M., Orlando, J. J., Tyndall, G. S., Møgelburg, T. E., Sehested, J. and Nielsen, O. J.: J. Phys. Chem. 100, 18116, 1996. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4224 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.55-61 RO + NO→ RO + NO (1) 2 2 RO + NO + M→ RONO + M (2) 2 2 (R = CH F, CHF , CF , CH FCHF, CHF CF , CF CHF, CF CF ) 2 2 3 2 2 2 3 3 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 Reaction k/cm molecule s Temp./K Reference Technique/Comments Number Absolute Rate Coefﬁcients IV.A1.55 R=CH F −11 (1.25± 0.13)× 10 295 Sehested et al., 1993 PR-AS (a) IV.A1.56 R=CHF −11 (1.26± 0.16)× 10 295 Sehested et al., 1993 PR-AS (a) IV.A1.57 R=CF −11 (1.78± 0.36)× 10 295 Plumb and Ryan, 1982 DF-MS (b) −11 −(1.2±0.2) 1.45× 10 (T /298) 230-430 Dognon et al., 1985 PLP-MS (c) −11 (1.45± 0.20)× 10 298 −11 (1.53± 0.30)× 10 290 Peeters et al., 1992 DF-MS (d) −11 (1.68± 0.26)× 10 295 Sehested and Nielsen, 1993 PR-AS (a) −11 (1.53± 0.20)× 10 297 Bevilacqua et al., 1993 F-CIMS (e) −11 (1.57± 0.38)× 10 298 Turnipseed et al., 1994 PLP-LIF (f) −11 (1.57± 0.31)× 10 293 Bhatnagar and Carr, 1994 FP-MS (g) −11 (1.76± 0.35)× 10 298 Bourbon et al., 1996 DF-LIF (h) −11 (1.6± 0.3)× 10 298 Louis et al., 1999 DF-MS (i) IV.A1.58 R=CH FCHF −12 > 8.7× 10 296 Wallington et al., 1994 PR-AS (a) IV.A1.59 R=CHF CF 2 2 −12 > (9.7± 1.3)× 10 295 Sehested et al., 1993 PR-AS (a) IV.A1.60 R=CF CHF −11 (1.28± 0.36)× 10 298 Wallington and Nielsen, 1991 PR-AS (a) −11 (1.31± 0.30)× 10 324 Bhatnagar and Carr, 1995 FP-MS (j) IV.A1.61 R=CF CF 3 2 −11 > (1.07± 0.15)× 10 295 Sehested et al., 1993 PR-AS (a) Branching Ratios IV.A1.57 R=CF k /k= (0.0167± 0.0027) 295 Nishida et al., 2004 P-FTIR (k) Comments (a) k determined from +d [NO ]/dt at a total pressure of 1 bar. (b) k was independent of pressure over the range 2.5–6.8 mbar. (c) No signiﬁcant pressure dependence in k over the range 1.3–13 mbar was observed. (d) Fast-ﬂow system with molecular beam sampling MS at a total pressure of 2.7 mbar. k was derived from decay of CF O 3 2 and appearance of NO . (e) k determined from decay of CF O in the presence of NO; pressure range 1.1–2.7 mbar. 3 2 (f) Photolysis of CF Br in the presence of O and NO at 93 mbar total pressure. k was obtained by ﬁtting the measured CF O 3 2 3 radical temporal proﬁle, with formation through CF O + NO and loss through CF O + NO. 3 2 3 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4225 (g) Photolysis of (CF CO) O in the presence of O , N and NO at 2.7–40 mbar total pressure. k obtained from the kinetics 3 2 2 2 of CF O removal and CF O formation. k was independent of pressure in the studied range. 3 2 3 (h) CF O generated from F + CHF reaction, with k determined from the formation kinetics of CF O when NO added; 3 2 3 3 pressure range 1.1–4.0 mbar. (i) CF O generated from F + CHF reaction, with k determined from the removal kinetics of CF O when NO added; 3 2 3 3 2 pressure range 0.9–4.0 mbar. (j) Photolysis of Cl in the presence of CF CH F, O , N and NO at 16–33 mbar total pressure. k was obtained from the 2 3 2 2 2 formation kinetics of NO . k was independent of pressure in the studied range. (k) CF O generated from the UV photolysis of CF N CF in excess NO, N and O at 930 mbar. Branching ratio determined 3 2 3 2 3 2 2 from the relative yields of CF ONO and COF . 3 2 2 Preferred Values R = CH F −11 3 −1 −1 k = 1.3× 10 cm molecule s at 298 K. 1log k =±0.3 at 298 K. R = CHF −11 3 −1 −1 k = 1.3× 10 cm molecule s at 298 K. 1log k =±0.3 at 298 K. R = CF −11 −1.2 3 −1 −1 k = 1.6× 10 (T /298) cm molecule s over the temperature range 230–430 K. 1log k =±0.1 at 298 K. 1n =±0.5. R = CH FCHF −12 3 −1 −1 k > 9× 10 cm molecule s at 298 K. R = CHF CF 2 2 −11 3 −1 −1 k > 1× 10 cm molecule s at 298 K. R = CF CHF −11 3 −1 −1 k = 1.3× 10 cm molecule s at 298 K. 1log k =±0.2 at 298 K. R = CF CF 3 2 −11 3 −1 −1 k > 1× 10 cm molecule s at 298 K. Comments on Preferred Values R = CH F, CHF , CHF CF , CF CF 2 2 2 2 3 2 The preferred values are the rounded-off rate coefﬁcients determined by Sehested et al. (1993). R = CF The preferred values are based on the temperature dependent data of Dognon et al. (1985), adjusted to ﬁt a k value based on the determinations of Plumb and Ryan (1982), Dognon et al. (1985), Peeters et al. (1992), Sehested and Nielsen (1993), Bevilacqua et al. (1993), Turnipseed et al. (1994), Bhatnagar and Carr (1994), Bourbon et al. (1996) and Louis et al. (1999). www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4226 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry R = CH FCHF The preferred value is the rounded-off lower limit of Wallington et al. (1994). R = CF CHF The preferred value is the rounded-off rate coefﬁcient determined by Wallington and Nielsen (1991). The temperature dependence expressions are given in the form favoured by Dognon et al. (1985), and subsequently adopted by others, which best describe the measured data. Comparison of the reported rate coefﬁcients with those for the corresponding alkyl peroxy radicals, CH O and C H O , indicates that the presence of a α-halogen substituent typically enhances k 3 2 2 5 2 298 by a factor of about 1.5–2, with the reactions also possessing a similar dependence on temperature where comparison is possible. Although not so marked, it appears that additional α-halogen substituents result in further slight enhancements to k . Similarly to small alkyl peroxy radicals, the observations indicate that the reactions are dominated by the RO-forming channel (1). Dognon et al. (1985) measured quantum yields for NO greater than unity for all the RO radicals studied; 2 2 suggesting that the RO + NO reactions mainly form RO and NO , with additional NO being produced from secondary 2 2 2 chemistry. Nishida et al. (2004) have observed formation of a small yield 1.7 ± 0.3% of CF ONO from the reaction of 3 2 CF O with NO, conﬁrming the existence of channel (2) at 930 mbar pressure. This suggests that the reactions of the C 3 2 1 and C halogenated RO radicals will generally have minor channels forming RONO , but additional studies are required to 2 2 2 conﬁrm this. References Bhatnagar, A. and Carr, R.W.: Chem. Phys. Lett. 231, 454, 1994. Bhatnagar, A. and Carr, R.W.: Chem. Phys. Lett. 238, 9, 1995. Bevilacqua, T. J., Hanson, D. R. and Howard, C. J.: J. Phys. Chem. 97, 3750, 1993. Bourbon, C., Brioukov, M., Hanoune, B., Sawerysyn, J. P. and Devolder, P.: Chem. Phys. Lett. 254, 203, 1996. Dognon, A. M., Caralp, F. and Lesclaux, R.: J. Chim. Phys. 82, 349, 1985. Louis, F., Burgess, D. R., Rayez, M. T. and Sawerysyn, J. P.: Phys. Chem. Chem. Phys. 1, 5087, 1999. Nishida, S., Takahashi, K., Matsumi, Y., Chiappero, M., Arguello, G., Wallington, T. J., Hurley, M. D. and Ball J. C.: Chem. Phys. Lett. 388, 242, 2004. Peeters, J., Vertommen, J. and Langhans, I.: Ber. Bunsenges. Phys. Chem. 96, 431, 1992. Plumb, I. C. and Ryan, K. R.: Chem. Phys. Lett. 92, 236, 1982. Ryan, K. R. and Plumb, I. C.: Int. J. Chem. Kinet. 16, 591, 1984. Sehested, J. and Nielsen, O. J.: Chem. Phys. Lett. 206, 369, 1993. Sehested, J., Nielsen, O. J. and Wallington, T. J.: Chem. Phys. Lett. 213, 457, 1993. Turnipseed, A. A., Barone, S. B. and Ravishankara, A. R.: J. Phys. Chem. 98, 4594, 1994. Wallington, T. J. and Nielsen, O. J.: Chem. Phys. Lett. 187, 33, 1991. Wallington, T. J., Hurley, M. D., Ball, J. C., Ellermann, T., Nielsen, O. J. and Sehested, J.: J. Phys. Chem. 98, 5435, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4227 IV.A1.62 CF O + NO + M→ CF O NO + M 3 2 2 3 2 2 ◦ −1 1H = -105 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −29 −4.7 (2.7± 0.8)× 10 (T /298) [O ] 233-373 Caralp et al., 1988 PLP-MS (a) −33 6.3× 10 exp(2710/T ) [N ] 264-297 Mayer-Figge et al., 1996 (b) −29 −9.1 5.6× 10 (T /298) [N ] Comments (a) Pulsed laser photolysis-MS study in 1-10 Torr O . Extrapolation with F = exp(-T /416), i.e., F = 0.49 at 298 K, and k 2 c c ∞ −12 −0.72 3 −1 −1 = 8.9× 10 (T /298) cm molecule s from RRKM model. (b) From measurements of the reverse dissociation of CF O NO . Equilibrium constants K = 3.80 × 10 exp(-12140/T ) 3 2 2 c 3 −1 −1 cm molecule s derived by combining the dissociation data with the recombination data from Caralp et al. (1988) over the falloff curve, assuming equal results for the bath gases N and O . Extrapolation with F = 0.31 and k = 7.7× 2 2 c ∞ −12 3 −1 −1 10 cm molecule s . Preferred Values −29 −9 3 −1 −1 k = 5.6× 10 (T /298) [N ] cm molecule s over the temperature range 200-300 K. 0 2 Reliability 1 log k =± 0.2 at 298 K. 1 n =± 3. Comments on Preferred Values The data by Mayer-Figge et al. (1996) are preferred because they cover a much broader part of the falloff curve and employ a more reasonable value of F = 0.31, thus allowing for a better extrapolation to the low pressure limit. Nevertheless, the rate data from Caralp et al. (1988) and Mayer-Figge et al. (1996) are identical over the range 1.3–13 mbar because both sets of data have been used for the conversion from dissociation to recombination rate coefﬁcients. High-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 −0.72 8.9× 10 (T /298) 233-373 Caralp et al., 1988 PLP-MS (a) −12 −0.67 7.7× 10 (T /298) 264-297 Mayer-Figge et al., 1996 (b) www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4228 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments (a) See comment (a) for k . (b) See comment (b) for k . Preferred Values −12 −0.67 3 −1 −1 k = 7.7× 10 (T /298) cm molecule s over the temperature range 260-300 K. Reliability 1 log k =± 0.2 at 298 K. 1 n =± 0.5. Comments on Preferred Values See Comments on Preferred Values for k . References Caralp, F., Lesclaux, R., Rayez, M.-T., Rayez, J.-C. and Forst, W.: J. Chem. Soc. Faraday Trans 2, 84, 569, 1988. Mayer-Figge, A., Zabel, F. and Becker, K.H.: J. Phys. Chem., 100, 6587, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4229 IV.A1.63 CF O NO + M→ CF O + NO + M 3 2 2 3 2 2 ◦ −1 1H = 105 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data −1 k /s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −5 2.4× 10 exp(-9430/T ) [N ] 264-297 Mayer-Figge et al., 1996 (a) Comments (a) Preparation of CF O NO by in situ photolysis of CF I/O /NO /N mixtures in a 420 l reactor. Time dependence of 3 2 2 3 2 2 2 CF O NO decay monitored by IR absorption. Measurements in 3.7–1013 mbar of N evaluated with F = 0.31, N = 3 2 2 2 c c 16 −1 ◦ 1.19, and k = 1.49 × 10 exp(-11940/T ) s . Similar results in O . Analysis of equilibrium constant gives 1H = ∞ 2 −1 102.7 (± 2.0) kJ mol . Preferred Values −5 −1 k = 2.5× 10 exp(-9430/T ) [N ] s over the temperature range 260-300 K. 0 2 −19 −1 k = 4.5× 10 [N ] s at 298 K. 0 2 Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 250 K. Comments on Preferred Values The single measurement falls in line with data for related reactions. In addition, it could be evaluated theoretically leading to realistic molecular parameters. Because no unusual complications were observed, the data appear reliable. The observed part of the falloff curve could well be represented with F and k such as given in comment (a) for k . c ∞ 0 High-pressure rate coefﬁcients Rate coefﬁcient data −1 k /s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients 1.49× 10 exp(-11940/T ) 264-297 Mayer-Figge et al., 1996 (a) Comments (a) See comment (a) for k . www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4230 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values 16 −1 k = 1.5× 10 exp(-11940/T ) s over the temperature range 260-300 K. −2 −1 k = 6.0× 10 s at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 250 K. Comments on Preferred Values See Comments on Preferred Values for k . The theoretical analysis by Mayer-Figge et al. (1996) supersedes the more specu- lative earlier analysis by Destriau and Troe (1990). The falloff curve is constructed with the ﬁtted F = 0.31 and N = 1.19 in c c good agreement with the recommendation given in the Introduction. References Destriau, M. and Troe, J.: Int. J. Chem. Kinet., 22, 915, 1990. Mayer-Figge, A., Zabel, F. and Becker, K. H.: J. Phys. Chem., 100, 6587, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4231 IV.A1.64 CH FO + CH FO → CH FOH + HC(O)F + O (1) 2 2 2 2 2 2 → CH FO + CH FO + O (2) 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 k = 3.3× 10 exp[(700± 100)/T ] 228-380 Dagaut et al., 1988 FP-UVA (a,b) obs −12 k = (3.07± 0.65)× 10 298 obs −12 k = (4.01± 0.52)× 10 298 Wallington et al., 1992 PR-UVA (a,c) obs Branching Ratios k /k > 0.77 298 Wallington et al., 1992 UVP-FTIR (d) Comments (a) k is based on the measured overall second-order decay of CH FO , deﬁned by -d[CH FO ]/dt = 2k [CH FO ] . As obs 2 2 2 2 obs 2 2 described in detail by Lesclaux (1997), HO radicals formed from the subsequent chemistry of CH FO (formed from 2 2 channel (2)) are expected to lead to secondary removal of CH FO . The true value of k is expected to fall in the range 2 2 k /(1 + α) < k < k , where α = k /k. obs obs 2 (b) Flash photolysis of Cl in the presence of CH F-O -N mixtures at total pressures of 33–533 mbar. CH FO radicals 2 3 2 2 2 2 −18 2 −1 were monitored by UV absorption with σ = (3.72± 0.45)× 10 cm molecule . 240 nm (c) Pulse radiolysis study of CH F-O -SF mixtures at a total pressure of 1000 mbar. CH FO radicals were monitored by 3 2 6 2 2 −18 2 −1 UV absorption with σ = (4.11± 0.67)× 10 cm molecule . 240 nm (d) CH FO radicals were generated from the steady-state photolysis of Cl -CH F mixtures at 933 mbar pressure of air. The 2 2 2 3 decay of CH F and the formation of products was monitored by FTIR spectroscopy. No CH FOH was observed within 3 2 the detection limits of the apparatus. Signiﬁcant amounts of HC(O)F were observed (86± 5%) and, in experiments with high conversions, CH FOOH was observed (11± 4%). Preferred Values −12 3 −1 −1 k = 2.6× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 2.5× 10 exp(700/T ) cm molecule s over the temperature range 220-380 K. k /k = 1.0 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. +0.0 1 (k /k) = at 298 K. −0.2 Comments on Preferred Values In the product study of Wallington et al. (1992) no formation of CH FOH was observed, showing that channel (1) is not of major importance at 298 K. The high yields of HC(O)F are also consistent with the dominance of channel (2), followed by reaction of CH FO with O to form HC(O)F and HO . A product study of the CH FO + HO reaction (Wallington et al., 2 2 2 2 2 2 1994) has shown that only ca. 30% of that reaction produces CH FO H and O , with the remainder forming HC(O)F, H O 2 2 2 2 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4232 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry and O . The low yields of CH FO H observed by Wallington et al. (1992) are thus partially explained by this, but also suggest 2 2 2 that HO is probably removed by its self reaction in competition with reaction with CH FO . 2 2 2 The preferred value of k at 298 K is derived from the k values reported by Dagaut et al. (1988) and Wallington et al. obs −18 2 −1 (1992), adjusted to be consistent with the re-evaluation of σ (CH FO ) = 4.03 × 10 cm molecule by Nielsen 240 nm 2 2 and Wallington (1997). Similar to a procedure adopted by Lesclaux (1997) for peroxy radicals for which the self reaction −12 3 −1 −1 rate coefﬁcients are ≥ ca. 2 × 10 cm molecule s , k is estimated to be k /(1 + 0.5(k /k)), with this approximation obs 2 assuming that the secondary reaction of HO with CH FO competes equally with its removal via HO + HO . The reliability 2 2 2 2 2 range reﬂects that k has been derived by this approximate procedure. The preferred value of E/R is based on the k expression obs of Dagaut et al. (1988). This assumes that the above competition remains valid over the entire temperature range, consistent with the CH FO and HO self reactions, and reaction of CH FO with HO possessing similar temperature dependences. 2 2 2 2 2 2 References Dagaut, P., Wallington, T. J. and Kurylo, M. J.: Int. J. Chem. Kinet. 20, 815, 1988. Lesclaux, R.: Combination of peroxyl radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z. B., John Wiley and Sons, 1997. Nielsen, O. J. and Wallington, T. J.: Ultraviolet absorption spectra of peroxy radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z. B., John Wiley and Sons, 1997. Wallington, T. J., Ball, J. C., Nielsen, O. J. and Bartkiewicz, E.: J. Phys. Chem. 96, 1241, 1992. Wallington, T. J., Hurley, M. D., Schneider, W. F., Sehested, J. and Nielsen, O. J.: Chem. Phys. Lett. 218, 34, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4233 IV.A1.65 CHF O + CHF O → CHF OH + C(O)F + O (1) 2 2 2 2 2 2 2 → CHF O + CHF O + O (2) 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 k = (5.0± 0.7)× 10 298 Nielsen et al., 1992 PR-UVA (a,b) obs Branching Ratios k /k ≈ 1.0 298 Nielsen et al., 1992 UVP-FTIR (c) Comments (a) k is based on the measured overall second-order decay of CHF O , deﬁned by -d[CHF O ]/dt = 2k [CHF O ] . As obs 2 2 2 2 obs 2 2 described in detail by Lesclaux (1997), HO radicals formed from the subsequent chemistry of CHF O (formed from 2 2 channel (2)) are expected to lead to secondary removal of CHF O . The true value of k is expected to fall in the range 2 2 k /(1 + α) < k < k , where α = k /k. obs obs 2 (b) Pulse radiolysis study of CH F -O -SF mixtures at a total pressure of 1000 mbar. CHF O radicals were monitored by 2 2 2 6 2 2 −18 2 −1 UV absorption with σ = (2.66± 0.46)× 10 cm molecule . 240 nm (c) CHF O radicals were generated from the steady-state photolysis of Cl -CH F mixtures in the presence of air at a total 2 2 2 2 2 pressure of 933 mbar. The decay of CH F and the formation of C(O)F were monitored by FTIR spectroscopy. The 2 2 2 yield of C(O)F was 104± 2% of the removal of CH F . 2 2 2 Preferred Values −12 3 −1 −1 k = (2.5–5)× 10 cm molecule s at 298 K. k /k ≈ 1.0 at 298 K. Comments on Preferred Values We have recommended a range of values for the rate coefﬁcient at 298 K, based on the determination by Nielsen et al. (1992). The upper limit is the measured value of k with no correction for possible secondary CHF O removal by HO radicals, and obs 2 2 2 the lower limit is a factor of two less than the upper limit, corresponding to a maximum correction for the HO radical reaction. The product study in the same paper (Nielsen et al., 1992) showed that the only carbon-containing product was C(O)F , formed by the reaction CHF O + O → C(O)F + HO , indicating that channel (2) is the predominant pathway. The absence 2 2 2 2 of the product CHF O H expected from the reaction CHF O + HO → CHF O H + O , raises several possibilities, including 2 2 2 2 2 2 2 2 a slow reaction between CHF O and HO radicals or an alternative reaction pathway, such as CHF O + HO → C(O)F + 2 2 2 2 2 2 2 H O + O . More information is needed on the kinetics and mechanism of the CHF O + HO reaction to deﬁne k and k /k 2 2 2 2 2 2 more accurately. References Lesclaux, R.: Combination of peroxyl radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z. B., John Wiley and Sons, 1997. Nielsen, O. J., Ellermann, T., Bartkiewicz, E., Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett. 192, 82, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4234 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.66 CF O + CF O → CF O + CF O + O 3 2 3 2 3 3 2 ◦ −1 1H = -83.2 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (1.8± 0.5)× 10 295 Nielsen et al., 1992 PR-UVA (a) −12 1.8× 10 298 Maricq and Szente, 1992a FP-UVA (b) −12 (1.8± 0.5)× 10 297 Maricq and Szente, 1992b FP-UVA (c) −12 (1.2± 0.3)× 10 298 Biggs et al., 1997 DF-LIF/MS (d) −12 (2.25± 0.3)× 10 295 Sehested et al., 1997 PR-UVA (e) Comments (a) Pulse radiolysis study of CHF -O -SF mixtures at a total pressure of 1000 mbar. CF O radicals were monitored by 3 2 6 3 2 −18 2 −1 UV absorption with σ = (2.06 ± 0.40) × 10 cm molecule , and an observed rate coefﬁcient, k = (3.6 ± 230 nm obs −12 3 −1 −1 0.9)× 10 cm molecule s , was derived from the decay in absorption. Associated FTIR product studies using the photolysis of F -CHF -O -N mixtures demonstrated quantitative formation of CF OOOCF , which was explained by 2 3 2 2 3 3 the secondary reaction of CF O with CF O . The cited value of k is thus 0.5 k , to take account of this secondary loss 3 3 2 obs of CF O . 3 2 (b) Flash photolysis of CHF -F -O mixtures with time-resolved absorption spectroscopy for the detection of CF O radicals, 3 2 2 3 2 −18 2 −1 −12 3 −1 −1 with σ = (4.3 ± 0.3) × 10 cm molecule . A value of k = (3.1 ± 0.25) × 10 cm molecule s 210 nm obs was determined from the time-dependence of the CF O radical absorbance. The cited value of k was obtained from a 3 2 simulation in which secondary removal of CF O was explicitly represented. 3 2 (c) Flash photolysis of F in the presence of N , O , He, and CF CFH . Secondary generation of CF O in the system 2 2 2 3 2 3 2 occurred by the reaction CF CHFO → CF + HCOF, followed by CF + O + M → CF O + M. CF O radicals were 3 3 3 2 3 2 3 2 −12 3 −1 −1 monitored by UV absorption, and the 298 K value of k = 3.1 × 10 cm molecule s , derived in the authors’ obs previous study (Maricq and Szente, 1992a), was shown to provide a good description of the time dependence of the formation and removal of CF O . The previous value (Maricq and Szente, 1992a) of the rate coefﬁcient for the elementary 3 2 reaction, k, was therefore conﬁrmed and assigned the cited error limits. Additional measurements suggested that k obs decreases with increasing temperature. (d) Experiments performed at pressures in the range 1.3 to 4 mbar. CF O radicals were produced by the F + CHF reaction 3 2 3 or the F + CF I reaction, with subsequent addition of O . CF O radicals were monitored by titration to NO following 3 2 3 2 2 reaction with excess NO, with detection of NO by either LIF or MS. An observed rate coefﬁcient, k = (2.0 ± 1.0) × 2 obs −12 3 −1 −1 10 cm molecule s , was derived from the decay in CF O . The cited value of k was obtained from a simulation 3 2 in which secondary removal of CF O was explicitly considered. 3 2 (e) Pulse radiolysis study of CHF -O -SF mixtures at a total pressure of 1000 mbar. CF O radicals were monitored by UV 3 2 6 3 2 −18 2 −1 absorption with σ = 3.43× 10 cm molecule . The cited value of k was derived from simulation of the decay 230 nm in absorption, using a chemical mechanism in which secondary removal of CF O was explicitly represented. 3 2 Preferred Values −12 3 −1 −1 k = 1.5× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.3 at 298 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4235 Comments on Preferred Values The reported quantitative formation of CF OOOCF from CHF oxidation, in the product study of Nielsen et al. (1992) is 3 3 3 consistent with the self-reaction of CF O proceeding via formation of CF O radicals, which react with CF O . 3 2 3 3 2 The ﬁve reported values of k are in reasonable accord, covering a range of approximately two. The discharge-ﬂow determi- nation of Biggs et al. (1997) lies at the low end of the range, and this may be indicative a pressure dependence of the reaction. Biggs et al. (1997) performed QRRK calculations, based on the reaction proceeding via a [CF O CF ] intermediate and 3 4 3 estimated that the high pressure limiting k (achieved at ca. 35–70 mbar) is ca. 15% greater than their measured value, i.e. (1.4 −12 3 −1 −1 ± 0.4)× 10 cm molecule s . The observed range in reported k values may also be reduced by re-evaluating the results of the UV absorption studies (Nielsen et al., 1992; Maricq and Szente, 1992a, b; Sehested et al., 1997) using the recommended CF O absorption cross sections reported by Nielsen and Wallington (1997), which are somewhat lower than those applied 3 2 −12 by Maricq and Szente (1992a, b) and Sehested et al. (1997). This leads to respective revised values of k of 1.5 × 10 and −12 3 −1 −1 1.4 × 10 cm molecule s in those studies, and a much improved general agreement among the reported studies. The preferred value of k is therefore based on the re-evaluations of the UV absorption studies and the estimated high pressure value of Biggs et al. (1997). Maricq and Szente (1992b) obtained limited evidence that k possesses a weak negative temperature obs coefﬁcient, but further temperature dependence studies are required to quantify this. References Biggs, P., Canosa-Mas, C. E., Frachebound, J. M., Percival, C. J., Wayne, R. P. and Shallcross, D. E.: J. Chem. Soc. Faraday Trans., 93, 379, 1997. Maricq, M. M. and Szente, J. J.: J. Phys. Chem., 96, 4925, 1992a. Maricq, M. M. and Szente, J. J.: J. Phys. Chem., 96, 10862, 1992b. Nielsen, O. J. and Wallington, T. J.: Ultraviolet absorption spectra of peroxy radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z. B., John Wiley and Sons, 1997. Nielsen, O. J., Ellermann, T., Sehested, J., Bartkiewiecz, E., Wallington, T. J. and Hurley, M. D.: Int. J. Chem. Kinet., 24, 1009, 1992. Sehested, J., Møgelberg, T., Fagerstrom, K., Mahmoud, G. and Wallington, T. J.: Int. J. Chem. Kinet., 29, 673, 1997. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4236 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.67 CF O + CF CHFO → CF OH + CF COF + O (1) 3 2 3 2 3 3 2 → CF O + CF CHFO + O (2) 3 3 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (8± 3)× 10 297 Maricq and Szente, 1992 (a) Comments (a) Flash photolysis of F in the presence of CF CH F-O -N -He mixtures. CF CHFO radicals were monitored by UV 2 3 2 2 2 3 2 −18 2 −1 absorption with σ = (5.2 ± 0.3) × 10 cm molecule . The derived value of k listed above was obtained by 213 nm modeling the decay of CF CFHO radicals and the formation and decay of CF O radicals. 3 2 3 2 Preferred Values −12 3 −1 −1 k = 8× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.5 at 298 K. Comments on Preferred Values The preferred value of the rate coefﬁcient at 298 K seems reasonable, but requires independent conﬁrmation. Maricq and Szente (1992) assumed that the reaction proceeds entirely by channel (2) on the basis of studies of the self-reactions of CF O 3 2 and CF CHFO radicals. 3 2 References Maricq, M. M. and Szente, J. J.: J. Phys. Chem., 96, 10862, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4237 IV.A1.68 CHF CF O + CHF CF O → CHF CF O + CHF CF O + O 2 2 2 2 2 2 2 2 2 2 2 Rate coefﬁcient data 3 −1 −1 k/ cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 k = (2.7± 0.6)× 10 298 Nielsen et al., 1992a PR-UVA (a) obs Comments (a) Pulse radiolysis study of CHF CHF -O -SF mixtures at a total pressure of 1000 mbar. CHF CF O radicals were 2 2 2 6 2 2 2 −18 2 −1 monitored by UV absorption with σ = (3.2 ± 0.5) × 10 cm molecule . k is based on the measured overall 230 obs second-order decay in absorption at 230 nm, which was deﬁned as -d[CHF CF O ]/dt = 2k [CHF CF O ] . Product 2 2 2 obs 2 2 2 studies were also performed on the steady-state photolysis of Cl in the presence of CHF CHF -air mixtures at 933 mbar 2 2 2 total pressure. The decay of CHF CHF and the formation of COF , the only carbon-containing product observed, were 2 2 2 monitored by FTIR spectroscopy. The yield of COF was 98± 2% relative to the decay of CHF CHF . 2 2 2 Preferred Values No recommendation Comments on Preferred Values Although the value of k reported by Nielsen et al. (1992a) is likely to be indicative of the magnitude of the self-reaction rate obs coefﬁcient for CHF CF O , the probable formation of CHF O and HO radicals from the subsequent chemistry (see below) 2 2 2 2 2 2 is expected to lead to secondary removal of CHF CF O , but also interferences in the absorption traces at 230 nm, because the 2 2 2 spectra for all three peroxy radicals are similar. These two factors have opposing inﬂuences on k , and it is not possible to obs derive k without a detailed understanding of the rates and mechanisms of the secondary processes and appropriate simulations of the system. No ﬁrm recommendation for k can currently be made. The product study of Nielsen et al. (1992a) demonstrated approximately 100% formation of COF from the oxidation of CHF CHF , consistent with exclusive formation of CHF CF O from the self-reaction of CHF CF O , followed by decompo- 2 2 2 2 2 2 2 sition to form COF and CHF . The CHF radicals form CHF O radicals, which are known (Nielsen et al., 1992b) to interact 2 2 2 2 2 via their self-reaction, resulting in the formation of COF and HO from the subsequent reaction of CHF O with O . However, 2 2 2 2 it is probable that CHF O is also converted to CHF O via reaction with CHF CF O in the system. HO radicals, generated 2 2 2 2 2 2 2 from CHF O + O , potentially also react with both CHF CF O and CHF O , in competition with their self-reaction. The 2 2 2 2 2 2 2 absence of the products CHF CF O H and CHF O H, which might be formed in these reactions, raises several possibilities: 2 2 2 2 2 the reactions of HO with CHF CF O and CHF O may be too slow to compete with the self-reaction, or they may proceed 2 2 2 2 2 2 by alternative pathways leading to COF formation. More information is therefore needed on the kinetics and mechanism of the secondary reactions, in addition to further kinetics studies of the title reaction, to allow k to be deﬁned more accurately. References Nielsen, O. J., Ellermann, T., Sehested, J. and Wallington, T. J.: J. Phys. Chem. 96, 10875, 1992a. Nielsen, O. J., Ellermann, T., Bartkiewicz, E., Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett. 192, 82, 1992b. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4238 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.69 CF CHFO + CF CHFO → CF COF + CF CHFOH + O (1) 3 2 3 2 3 3 2 → CF CHFO + CF CHFO + O (2) 3 3 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 7.8× 10 exp[(605± 40)/T ] 211-372 Maricq and Szente, 1992 FP-UVA (a,b) −12 (7± 1.0)× 10 297 −12 (3.5± 0.8)× 10 295 Sehested et al., 1997 PR-UVA (a,c) Branching Ratios k /k = 0.28 273 Wallington et al., 1992 UVP-FTIR (d) k /k = 0.16 298 k /k = 0.05 353 k /k = 0.055 273 Tuazon and Atkinson, 1993 UVP-FTIR (e) k /k = 0.049 298 k /k = 0.046 320 Comments (a) k is deﬁned by -d[CF CHFO ]/dt = 2k[CF CHFO ] . 3 2 3 2 (b) Flash photolysis of F in the presence of N , O , He and CF CH F. CF CHFO radicals were monitored by UV absorption 2 2 2 3 2 3 2 −13 2 −1 with σ = (5.2± 0.3)× 10 cm molecule . The derived value of k listed above was obtained by modelling the 240 nm decay curves for CF CFHO radicals with a mechanism of 9 reactions. 3 2 (c) Pulse radiolysis study of CF CH F-O -SF mixtures at a total pressure of 1000 mbar. CF O radicals were monitored by 3 2 2 6 3 2 −18 2 −1 −18 2 −1 UV absorption at 220 nm (σ = 5.34× 10 cm molecule ), 230 nm (σ = 4.50× 10 cm molecule ) and 240 nm −18 2 −1 (σ = 3.06× 10 cm molecule ). The cited value of k was derived from simulation of the decay in absorption, using a chemical mechanism in which secondary removal of CF CHFO was explicitly represented. 3 2 (d) Steady-state photolysis of Cl in the presence of CF CFH -O mixtures at a total pressure of 933 mbar with FTIR analysis 2 3 2 2 of the products HC(O)F and CF C(O)F. The branching ratio was determined from the yields of CF C(O)F as a function 3 3 of added O , extrapolated to zero O partial pressure. 2 2 (e) Similar experiments to those of Comment (d). The branching ratios were derived from the yields of CF C(O)F in the presence of 787 mbar N and 1.3 mbar O . 2 2 Preferred Values −12 3 −1 −1 k = 4.7× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 6.2× 10 exp(605/T ) cm molecule s over the temperature range 210-375 K. k /k = 0.90, independent of temperature over the range 270-350 K. k /k = 0.10, independent of temperature over the range 270-350 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 200 K. 1 (k /k) = 1 (k /k) =± 0.05 over the temperature range 270-350 K. 1 2 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4239 Comments on Preferred Values The preferred value of k at 298 K is the average of the results of Maricq and Szente (1992) (based on their Arrhenius expression) and Sehested et al. (1997). The preferred Arrhenius expression for k is based on the E/R value from the study of Maricq and Szente (1992), combined with a pre-exponential factor adjusted to give the preferred value of k at 298 K. The temperature dependence reported by Maricq and Szente (1992), is based on temperature-independent branching ratios k /k and k /k over 1 2 the range 273–363 K. This is consistent with our recommendation of a temperature-independent branching ratio, k /k, which is the average of the experimental results of Wallington et al. (1992) and Tuazon and Atkinson (1993) over the range 273–353 K. The recommended value of k /k is inferred from that of k /k. It should be noted, however, that the results of Maricq and 2 1 Szente (1992) for k at 216 K are not consistent with temperature-independent branching ratios. The kinetics studies (Maricq and Szente, 1992; Sehested et al., 1997) report values of k at 298 K which differ by a factor of 1.7, and this is reﬂected in the assigned reliability range. Conﬁrmation of both the overall rate coefﬁcient and the branching ratios is required. References Maricq, M. M. and Szente, J. J.: J. Phys. Chem., 96, 10862, 1992. Sehested, J., Møgelberg, T., Fagerstrom, K., Mahmoud, G. and Wallington, T. J.: Int. J. Chem. Kinet., 29, 673, 1997. Tuazon, E. C. and Atkinson, R.: J. Atmos. Chem., 16, 301, 1993. Wallington, T. J., Hurley, M. D., Ball, J. C. and Kaiser, E. W.: Environ. Sci. Technol., 26, 1318, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4240 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A1.70 CF CF O + CF CF O → CF CF O + CF CF O + O 3 2 2 3 2 2 3 2 3 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 k = (2.10± 0.38)× 10 295 Sehested et al., 1993 PR-UVA (a) obs Comments (a) Pulse radiolysis study of CF CHF -O -SF mixtures at a total pressure of 1000 mbar. CF CF O radicals were monitored 3 2 2 6 3 2 2 −18 2 −1 by UV absorption with σ = (2.74± 0.46)× 10 cm molecule . k is based on the measured overall second- 230 nm obs order decay in absorption at 230 nm, which was deﬁned as -d[CF CF O ]/dt = 2k [CF CF O ] . Products studies were 3 2 2 obs 3 2 2 also performed on the steady-state photolysis of Cl in the presence of CF CHF -air mixtures at 933 mbar total pressure. 2 3 2 The decay of CF CHF and the formation of products were monitored by FTIR spectroscopy. The observed products 3 2 were C(O)F , CF O CF and CF O C F , and accounted for 100% of the CF CF H loss. 2 3 3 3 3 3 2 5 3 2 Preferred Values No recommendation Comments on Preferred Values Although the value of k reported by Sehested et al. (1993) is likely to be indicative of the magnitude of the self-reaction obs rate coefﬁcient for CF CF O , the formation of CF O and CF O radicals from the subsequent chemistry (see below) leads to 3 2 2 3 2 3 secondary removal of CF CF O , but also interferences in the absorption traces at 230 nm, because the spectra for CF CF O 3 2 2 3 2 2 and CF O are almost identical. These two factors have opposing inﬂuences on k , and it is not possible to derive k without a 3 2 obs detailed understanding of the rates and mechanisms of the secondary processes and appropriate simulations of the system. No ﬁrm recommendation for k can currently be made. The quantitative formation of C(O)F observed in the product study of Sehested et al. (1993) is consistent with exclusive formation of CF CF O from the self-reaction of CF CF O , followed by decomposition to form C(O)F and CF . The 3 2 3 2 2 2 3 CF radicals form CF O radicals, which are known (Nielsen et al., 1992) to interact via their self-reaction, resulting in the 3 3 2 formation of CF O. However, it is probable that CF O is also converted to CF O via reaction with CF CF O in the system. 3 3 2 3 3 2 2 Further removal of both CF CF O and CF O occurs via their reactions with CF O, which lead to the observed products 3 2 2 3 2 3 CF O C F and CF O CF (Sehested et al., 1993). More information is therefore needed on the kinetics and mechanism of 3 3 2 5 3 3 3 the secondary reactions, in addition to further kinetics studies of the title reaction, to allow k to be deﬁned more accurately. References Nielsen, O. J., Ellermann, T., Sehested, J., Bartkiewiecz, E., Wallington, T. J. and Hurley, M. D.: Int. J. Chem. Kinet., 24, 1009, 1992. Sehested, J., Ellermann, T., Nielsen, O. J., Wallington, T. J. and Hurley, M. D.: Int. J. Chem. Kinet. 25, 701, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4241 IV.A1.71 HC(O)F + hν → products Primary photochemical transitions ◦ −1 Reaction 1H /kJ.mol λ /nm threshold HC(O)F + hν → HF + CO (1) 8.7 13,730 → H + FCO (2) 458 261 → F + HCO (3) 515 232 Absorption cross-section data Wavelength range/nm References Comments 200-340 Rattigan et al., 1994 (a) 200–370 Meller and Moortgat, 1992 (b) Comments (a) The absorption spectrum of HC(O)F was studied using a puriﬁed sample of HC(O)F and recorded by diode array spec- troscopy with a resolution of 1.2 nm. The characteristic banded structure was recorded and the absolute cross-section at −20 2 −1 230 nm was σ = 6.65× 10 cm molecule using this resolution. The cross-section was independent of temperature in the range 233–318 K, in agreement with the earlier work of Giddings and Innes (1961). (b) Measurements of the spectrum of HC(O)F at a resolution of 0.02 nm. The spectrum consists of a vibrational progression of many sharp bands, with an origin of structured absorption at 268 nm and a maximum of intensity near 210 nm. The −19 2 −1 maximum value of σ = 1.5 × 10 cm molecule was observed at this resolution, which is in reasonable agreement −1 with the earlier work of Giddings and Innes (1961) who reported an absorption coefﬁcient of approximately 501 mol −1 −19 2 −1 cm (σ = 1.9× 10 cm molecule ) at the maximum. Quantum Yield Data There are no reported quantum yield data. Klimeck and Berry (1973) have observed infrared laser emission from HF following ﬂash photolysis of HC(O)F (λ >165 nm), indicating the occurrence of reactions (1) and/or (3). Reed et al. (1997) and Maul et al., (1999) have used H-atom photofragment translational spectroscopy in a pulsed molecular beam to study H atoms formed by channel (2) at∼ 243-247 nm. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4242 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values Absorption cross-sections for HC(O)F at 298 K 20 2 20 2 20 2 λnm 10 σ /cm λ/nm 10 σ /cm λ/nm 10 σ /cm 200 8.28 223 6.58 245 0.67 201 9.75 224 4.94 246 0.72 202 8.3 225 5.33 247 0.41 203 7.55 226 4.00 248 0.48 204 8.52 227 4.65 249 0.28 205 10.15 228 4.43 250 0.21 206 8.28 229 4.61 251 0.15 207 7.41 230 3.57 252 0.24 208 8.44 231 2.55 253 0.21 209 9.55 232 3.16 254 0.07 210 7.76 233 3.09 255 0.12 211 7.36 234 2.98 256 0.07 212 7.92 235 2.04 257 0.05 213 8.56 236 2.28 258 0.04 214 9.22 237 1.24 259 0.04 215 7.67 238 1.71 260 0.04 216 6.51 239 1.75 261 0.02 217 7.38 240 1.55 262 0.02 218 7.97 241 0.97 263 0.02 219 6.28 242 1.19 264 0.02 220 6.85 243 0.57 265 0.01 221 5.7 244 0.76 266 0.01 222 6.07 Quantum Yields for HC(O)F No recommendation. Comments on Preferred Values The preferred values for the cross-sections are based on the data for the absolute absorption cross-sections reported by Meller and Moortgat (1992). The listed values are averaged over 1 nm. The cross-sections of Rattigan et al. (1994) are higher than those of Meller and Moortgat (1992) by approximately a factor of 2 at 230 nm. Although the two studies are nominally at comparable resolution, the Rattigan et al. (1994) spectrum does not appear to contain all the features reported by Meller and Moortgat (1992), indicating possible errors. References Giddings, L. K. and Innes, K. K.: J. Molecular Spectr. 6, 528, 1961. Klimeck, E. and Berry, M. J.: Chem. Phys. Lett. 20, 141, 1973. Maul, C., Dietrich, C., Haas, T., Gericke, K. -H., Tachikawa, H., Langford, S. R., Kono, M., Reed, D. L., Dixon, R. N. and Ashfold, M. N. R. : Phys. Chem. Chem. Phys., 1, 767, 1999. Meller, R. and Moortgat, G.: ”Kinetics and Mechanisms for the Reactions of Halogenated Organic Compounds in the Troposphere,” Final Report to STEP-0004-C(EDB), 1992. Rattigan, O. V., Rowley, D. M., Wild, O., Jones, R. L. and Cox, R. A.: J. Chem. Soc. Faraday Trans., 90, 1818, 1994. Reed, C. K., Kono, M., Langford, S. R., Hancock, T. W. R., Dixon, R. N. and Ashfold, M. N. R.: J. Chem. Phys., 106, 6198, Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4243 IV.A1.72 C(O)F + hν → products Primary photochemical transitions ◦ −1 Reaction 1H /kJ.mol λ /nm threshold C(O)F + hν → FCO + F (1) 562 213 → CO + 2F (2) 683 175 → CF + O( P) (3) 700 171 Quantum yield data Measurement Wavelength range/nm References Comments 8 = 0.94± 0.06 193 Nolle ¨ et al., 1992, 1999 (a) 8 = 0.58± 0.05 210 Nolle ¨ et al., 1999 (b) 8 = 0.57± 0.05 210 (b,c) 8 = 0.07± 0.03 220 (b) 8 = 0.11± 0.02 220 (b,c) Comments (a) Laser photolysis at 296-298 K with initial C(O)F pressures of 10-30 mbar. Because of the high concentrations of FCO radicals in the laser photolysis experiments, formation of C(O)F was assumed to occur via the reaction FCO + FCO→ C(O)F + CO as observed in analogous experiments with C(O)FCl (Nolle ¨ et al., 1999). Therefore, the cited quantum yield is the measured value (0.47± 0.03) corrected for reformation of C(O)F from the FCO radical self-reaction. (b) Photolysis at 298K using a medium pressure mercury lamp-monochromator combination, with initial C(O)F pressures of 2.1–6.3 mbar. Because of the low concentrations of FCO radicals in these experiments, reformation of C(O)F from the reaction FCO + FCO → C(O)F + CO was not anticipated to be signiﬁcant, as conﬁrmed by observations in analogous experiments with C(O)FCl (Nolle ¨ et al., 1999). Therefore, the cited quantum yield is the measured value. (c) With added N diluent gas at pressures of 600–1000 mbar. Preferred Values Absorption cross-sections for C(O)F photolysis at 298 K 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 186.0 5.5 205.1 0.74 187.8 4.8 207.3 0.52 189.6 4.2 209.4 0.40 191.4 3.7 211.6 0.28 193.2 3.1 213.9 0.20 195.1 2.6 216.2 0.12 197.0 2.1 218.6 0.081 199.0 1.6 221.0 0.049 201.0 1.3 223.5 0.035 203.0 0.95 226.0 0.024 228.6 0.018 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4244 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Quantum Yields for C(O)F Photolysis at 298 K 8 = 0.94 at 193 nm 8 = 0.57 at 210 nm 8 = 0.09 at 220 nm Comments on Preferred Values The preferred values of the absorption cross sections are those reported by Molina and Molina (1982) over the wavelength range 184–199 nm and by Nolle ¨ et al. (1992) at longer wavelengths. The results of these two studies are in excellent agreement over the range 200–208 nm; from 208–225 nm the results of Molina and Molina (1982) are 15–25% smaller than those of Nolle ¨ −1 et al. (1992). The spectrum shows considerable structure; the values listed are averages over 500 cm intervals. Nolle et al. (1992; 1999) photolyzed C(O)F at three wavelengths in the range 193–220 nm. The overall quantum yield for loss of C(O)F , 2 2 which must be through channel (1), decreases monotonically with increasing wavelength. In the absence of conﬁrmatory data, the quantum yields measurd by Nolle ¨ et al. (1992; 1999) are recommended. References Molina, L. T. and Molina, M. J.: Results presented at the 182nd American Chemical Society National Meeting, New York, August 1982. Nolle, ¨ A., Heydtmann, H., Meller, R., Schneider, W. and Moortgat, G. K.: Geophys. Res. Lett. 19, 281, 1992. Nolle, ¨ A., Krumscheid, C. and Heydtmann, H.: Chem. Phys. Lett. 299, 561, 1999. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4245 IV.A1.73 CF CHO + hν → products Primary photochemical transitions ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF CHO + hν → CF + HCO (1) 3 3 → CF CO + H (2) → CHF + CO (3) Absorption cross-section data Wavelength range/nm References Comments 230-360 Meller et al., 1993 (a) 200–400 Selleva˙ g et al., 2004 (b) Quantum yield data Measurement Wavelength range/nm References Comments 8 < 0.02 290-400 Selleva˙ g et al., 2004 (c) Comments (a) Absolute absorption cross-sections were measured using a diode-array spectrometer over the temperature range 240–300 K. The UV spectrum of triﬂuoroacetaldehyde shows a broad band, centered at 305 nm and extending out to 355 nm. Values of σ were given at 5 nm intervals at 298 K. (b) Absolute absorption cross-sections were measured using a diode-array spectrometer over the temperature range 298±2 K, at a spectral resolution of 2 nm. The UV spectrum of triﬂuoroacetaldehyde shows a broad band, centered at∼300 nm and extending out to≥355 nm. Values of σ were given at 5 nm intervals at 298 K. (c) Photolysis of CF CHO in pure air in the presence of an HO radical tracer (di-n-butyl ether) in the∼200 m EUPHORE chamber facility under natural sunlight conditions. The measured ﬁrst-order loss rate of CF CHO during a∼3 hr period −6 −1 around solar noon was 7.74× 10 s , essentially identical to the leak obtained from monitoring the decay of SF . After correction for the leak rate and reaction with HO radicals, the calculated ﬁrst-order loss rate of CF CHO due to photolysis −7 −1 −5 −1 during this∼3 hr period was <8.5× 10 s , compared to the calculated photolysis rate of 5.5× 10 s using a unit quantum yield for photodissociation. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4246 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values Absorption cross-sections of CF CHO at 298 K 21 2 21 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 200 2.38 305 31.3 205 2.22 310 29.2 210 1.97 315 26.5 215 1.52 320 22.5 220 1.05 325 19.0 225 0.76 330 14.4 230 0.78 335 10.6 235 0.74 300 29.8 240 1.29 305 29.0 245 2.17 310 27.9 250 3.44 315 25.0 255 5.25 320 21.4 260 7.63 325 17.7 265 10.6 330 13.6 270 13.8 335 9.98 275 17.6 340 6.17 280 21.3 345 3.86 285 24.8 350 2.31 290 27.6 355 0.59 295 29.1 360 0.19 300 31.7 Quantum Yields of CF CHO No recommendation. Comments on Preferred Values The preferred values for the cross-sections are based on the data reported by Selleva˙ g et al. (2004), which are ∼7% higher than the data of Meller et al. (1993) at the peak absorpion at ∼300 nm and within the combined experimental uncertainties. No recommendation is made for the quantum yields but by analogy with other aldehydes, which show a similar absorption spectrum, any photodissociation at wavelengths > 300 nm is expected to be predominantly by channel (1). The only data concerning quantum yields are those of Selleva˙ g et al. (2004) for irradiation by natural sunlight at 290–400 nm, with an average photodissociation quantum yield of <0.02 for this wavelength region. The products of photolysis of CF CHO have been investigated by Dodd and Watson-Smith (1957). More recently, Richer et al. (1993) have studied the photooxidation of CF CHO and observed CHF , CO, CO and COF as products. Photodissociation 3 3 2 2 appears to occur predominantly via reaction (1). However, Richer et al. (1993) observed substantial yields (14%) of CHF in the 254 nm photolysis of CF CHO in air, indicating that channel (3) also occurs at that wavelength. References Dodd, R. E. and Watson-Smith, J.: J. Chem. Soc., 1465, 1957. Meller, R., Boglu, D. and Moortgat, G. K.: ”Kinetics and Mechanisms for the Reactions of Halogenated Organic Compounds in the Troposphere,” STEP-HALOCSIDE/AFEAS Workshop, Dublin, Eire, March 23-25, pp. 130-138, 1993. Richer, H., Sodeau, J. R. and Barnes, I.: ”Kinetics and Mechanisms for the Reactions of Halogenated Organic Compounds in the Troposphere,” STEP-HALOCSIDE/AFEAS Workshop, Dublin, Eire, March 23-25, pp. 182-188.1993. Selleva˙ g, S. R., Sidebottom, H. and Nielsen, C. J.: Phys. Chem. Chem. Phys., 6, 1243, 2004. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4247 IV.A1.74 CF C(O)F + hν → products Primary photochemical transitions ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF C(O)F + hν → CF + CFO (1) 3 3 → CF CO + F (2) Absorption cross-section data Wavelength range/nm References Comments 200–300 Rattigan et al., 1993 (a) 210–265 Meller et al., 1993 (b) Quantum yield data Measurement Wavelength range/nm References Comments 8 + 8 = 1.05± 0.05 254 Meller et al., 1993 (c) 1 2 8 + 8 = 1.02± 0.05 240 Bierbrauer et al., 1999 (d) 1 2 Comments (a) Absolute absorption cross sections were measured using a dual-beam diode array spectrometer over the temperature range 240-300 K. The UV spectrum of triﬂuoroacetyl ﬂuoride shows a single band extending out to 300 nm, where there is signiﬁcant temperature dependance, Values of σ were given at 5 nm intervals at 293 K and 238 K as well as temperature coefﬁcients in the long wavelength tail at λ > 270nm. (b) Absolute absorption cross sections were measured using a dual-beam diode array spectrometer at 298K. Cross sections were averaged over 1, 2 and 5 nm wavelength intervals. (c) Average of 10 measurements of the overall loss of CF C(O)F by photolysis in 1 atm air at 298 K, relative to the loss of C(O)Cl , for which 8 = 1. (d) Measurement of the overall loss of CF C(O)F in the presence of O (0.67-6.7 mbar) at 298 K. 3 2 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4248 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values Absorption cross-sections of CF C(O)F at 293K and 238 K 20 2 20 2 3 −1a λ/nm 10 σ /cm 10 σ /cm 10 B/K 293K 238K 200 9.35 9.46 -0.21 205 11.50 11.60 -0.16 210 12.88 13.10 -0.31 215 13.72 13.70 0.03 220 13.39 13.10 0.40 225 11.93 11.40 0.83 230 9.75 9.11 1.23 235 7.26 6.55 1.87 240 4.93 4.18 2.99 245 3.01 2.30 4.91 250 1.67 1.16 6.60 255 0.82 0.49 9.36 260 0.35 0.18 12.40 265 0.13 0.05 18.77 270 0.04 0.01 26.36 275 0.012 0.003 24.73 280 0.004 0.001 23.32 285 0.0016 0.0004 25.21 290 0.0008 0.00 295 0.0003 0.00 ln σ (T ) = ln σ (293 K) + B(T -293). Quantum Yields of CF C(O)F at 298 K 8 + 8 = 1.0 over the wavelength range 200–300 nm. 1 2 Comments on Preferred Values The preferred values for the cross-sections at 293 K are a simple average of the data reported by Rattigan et al. (1993) and Meller et al. (1993). The temperature dependence is based on the 238 K data of Rattigan et al. (1993). The quantum yield of unity is based on the data of Meller et al. (1993) and of Bierbrauer et al. (1999), and is assumed to apply over the wavelength region 200–300 nm. References Bierbrauer, K. L., Chiappero, M. S., Malanca, F. E. and Argullo, ¨ G. A.: J. Photobiol. A: Chem., 122, 73, 1999. Meller, R., Boglu, D. and Moortgat, G. K.: ”Kinetics and Mechanisms for the Reactions of Halogenated Organic Compounds in the Troposphere,” STEP-HALOCSIDE/AFEAS Workshop, Dublin, Eire, March 23-25, pp. 130-138, 1993. Rattigan, O. V., Wild, O., Jones, R. L. and Cox, R. A.: J. Photochem. Photobiol. A: Chem. 73, 1, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4249 Appendix 2: ClO Reactions IV.A2.75 1 3 O( D) + CHF Cl → O( P) + CHF Cl (1) 2 2 → ClO + CHF (2) → other products (3) ◦ −1 1H (1) = -190 kJ·mol ◦ −1 1H (2) = -92 kJ·mol Rate coefﬁcient data (k = k + k + k ) 1 2 3 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (0.95± 0.3)× 10 173-343 Davidson et al., 1978 PLP (a) −10 (1.08± 0.20)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios k /k= 0.28± 0.06 298 Warren et al., 1991 PLP-RF (b) k /k= 0.55± 0.10 298 Addison et al., 1979 PLP-UVA (c) Comments (a) Pulsed laser photolysis of O at 266 nm. O( D) atoms were monitored by time-resolved emission at 630 nm. 3 1 1 (b) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CHF Cl relative to that for O( D) + N . 2 2 2 2 (c) Quantitative yields of ClO were determined via the (5,0) band of the A π ← X π system. Preferred Values −10 3 −1 −1 k = 1.0× 10 cm molecule s independent of temperature over the range 170-350 K. k /k = 0.28 at 298 K. k /k = 0.55 at 298 K. Reliability 1 log k =± 0.1 over the temperature range 170-350 K. 1 (k /k) =± 0.1 at 298 K. 1 (k /k) =± 0.2 at 298 K. Comments on Preferred Values The preferred value of k is based on the results of Davidson et al. (1978) and the room temperature value of Warren et al. (1991). The preferred value of the branching ratio k /k is the value reported by Warren et al. (1991). The preferred value of the branching ratio k /k is the value reported by Addison et al. (1979). References Addison, M. C., Donovan, R. J. and Garraway, J.: J. Chem. Soc. Faraday Discuss., 67, 286, 1979. Davidson, J. A., Schiff, H. I., Brown, T. J. and Howard, C. J.: J. Chem. Phys., 69, 4277, 1978. Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett., 183, 403, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4250 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.76 O( D) + CHFCl → ClO + CHFCl (1) → other products (2) ◦ −1 1H (1) = -113 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (1.9± 0.6)× 10 188-343 Davidson et al., 1978 PLP (a) Branching Ratios k /k= 0.74± 0.15 298 Takahashi et al., 1996 PLP-LIF (b) Comments (a) Pulsed laser photolysis of O at 266 nm. O( D) atoms were monitored by time-resolved emission at 630 nm. (b) Branching ratio for ClO formation was determined by measurement of the LIF signal intensity of ClO normalized to that from O( D) + HCl. Preferred Values −10 3 −1 −1 k = 1.9× 10 cm molecule s independent of temperature over the range 180-350 K. k /k = 0.74 at 298 K. Reliability 1 log k =± 0.3 over the temperature range 180–350 K. 1 (k /k) =± 0.2 at 298 K. Comments on Preferred Values The preferred value of k is based on the results of Davidson et al. (1978). The preferred value of the branching ratio k /k is based on the results of Takahashi et al. (1996). References Davidson, J. A., Schiff, H. I., Brown, T. J. and Howard, C. J.: J. Chem. Phys., 69, 4277, 1978. Takahashi, K., Wada, R., Matsumi, Y. and Kawasaki, M.: J. Phys. Chem., 100, 10145, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4251 IV.A2.77 1 3 O( D) + CH CF Cl → O( P) + CH CF Cl (1) 3 2 3 2 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (2.15± 0.20)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios k /k= 0.26± 0.05 298 Warren et al., 1991 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CH CF Cl relative to that for O( D) + 3 2 N . Preferred Values −10 3 −1 −1 k = 2.2× 10 cm molecule s at 298 K. k /k = 0.26 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Warren etal. (1991). In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CH CF Cl was obtained. 3 2 References Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett., 183, 403, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4252 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.78 1 3 O( D) + CH CFCl → O( P) + CH CFCl (1) 3 2 3 2 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (2.58± 0.20)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios k /k= 0.31± 0.05 298 Warren et al., 1991 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CH CFCl relative to that for O( D) + 3 2 N . Preferred Values −11 3 −1 −1 k = 2.6× 10 cm molecule s at 298 K. k /k = 0.31 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Warren et al. (1991), the only published study of this reaction. In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CH CFCl was obtained. 3 2 References Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett., 183, 403, 1991. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4253 IV.A2.79 1 3 O( D) + CH ClCF → O( P) + CH ClCF (1) 2 3 2 3 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (1.20± 0.06)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios k /k= 0.20± 0.05 298 Warren et al., 1991 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CH ClCF relative to that for O( D) + 2 3 N . Preferred Values −10 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. k /k = 0.20 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Warren et al. (1991). In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CH ClCF was obtained. 2 3 References Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett., 183, 403, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4254 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.80 1 3 O( D) + CH ClCF Cl → O( P) + CH ClCF Cl (1) 2 2 2 2 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 k = (1.6± 0.6)× 10 297 Green and Wayne, 1976 RR (a) Comments (a) O( D) produced by photolysis of NO at 229 nm. 1(CH ClCF Cl)/1(N O) monitored by IR absorption spectroscopy. 2 2 2 2 1 1 Measured rate coefﬁcient ratio of k /k(O( D) + N O) = 1.4± 0.3 is placed on an absolute basis by use of k(O( D) + N O) 2 2 2 −10 3 −1 −1 = 1.16 × 10 cm molecule s (IUPAC, current evaluation). The cited rate coefﬁcient refers to chemical reaction only and does not include physical quenching. Preferred Values −10 3 −1 −1 k = 1.6× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.5 at 298 K. Comments on Preferred Values The preferred value of k is derived from the relative rate results reported by Green and Wayne (1976) in the only published study of this reaction. It should be noted that this rate coefﬁcient refers to chemical reaction only and does not include physical quenching of O( D). References Green, R. G. and Wayne, R. P.: J. Photochem., 6, 371, 1976. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4255 IV.A2.81 1 3 O( D) + CHFClCF → O( P) + CHFClCF (1) 3 3 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 (8.6± 0.4)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios k /k = 0.31± 0.10 298 Warren et al., 1991 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CHFClCF relative to that for O( D) + N . Preferred Values −11 3 −1 −1 k = 8.6× 10 cm molecule s at 298 K. k /k = 0.31 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.2 at 298 K. Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Warren et al. (1991), the only published study of this reaction. In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CHFClCF was obtained. References Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett., 183, 403, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4256 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.82 1 3 O( D) + CHCl CF → O( P) + CHCl CF (1) 2 3 2 3 → other products (2) ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (1.98± 0.15)× 10 298 Warren et al., 1991 PLP-RF Branching Ratios k /k = 0.21± 0.08 298 Warren et al., 1991 PLP-RF (a) Comments 3 1 1 (a) Branching ratio was determined from the ratio of the O( P) yield from O( D) + CHCl CF relative to that for O( D) + 2 3 N . Preferred Values −10 3 −1 −1 k = 2.0× 10 cm molecule s at 298 K. k /k = 0.21 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.2 at 298 K. Comments on Preferred Values The preferred value of k and the preferred value of the branching ratio k /k are based on the results of Warren et al. (1991). In these experiments, only O( P) was monitored and therefore no direct information relating to the products of the chemical reaction of O( D) + CHCl CF was obtained. 2 3 References Warren, R., Gierczak, T. and Ravishankara, A. R.: Chem. Phys. Lett.,183, 403, 1991. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4257 IV.A2.83 O( D) + CF Cl → ClO + CF Cl (1) 2 2 2 → O( P) + CF Cl (2) 2 2 ◦ −1 1H (1) = -123 kJ·mol ◦ −1 1H (2) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (1.45± 0.5)× 10 173-343 Davidson et al., 1978 PLP (a) −10 (1.4± 0.2)× 10 298 Force and Wiesenfeld, 1981 PLP-RA Branching Ratios k /k = 0.14± 0.07 298 Force and Wiesenfeld, 1981 PLP-RA (b) k /k = 0.87± 0.18 298 Takahashi et al., 1996 PLP-LIF (c) k /k = 0.19± 0.05 298 Takahashi et al., 1996 PLP-LIF (d) Comments (a) Pulsed laser photolysis of O at 266 nm. O( D) atoms were monitored by time-resolved emission at 630 nm. 1 3 (b) O( D) atoms were monitored by resonance absorption at 130.4 nm and compared to O( P) atoms in the presence of ozone 3 1 in He diluent where the O( P) atom yield from the O( D) + O reaction is 1.0. (c) Branching ratio for ClO formation was determined by measurement of the LIF signal intensity of ClO normalized to that from O( D) + HCl. 1 3 (d) Branching ratio for quenching of O( D) to O( P) was determined by comparison of the VUV-LIF signal intensity for CF Cl with that of N . 2 2 2 Preferred Values −10 3 −1 −1 k = 1.4× 10 cm molecule s independent of temperature over the range 170–350 K. k /k = 0.83 at 298 K. k /k = 0.17 at 298 K. Reliability 1 log k =± 0.1 over the temperature range 170–350 K. 1 (k /k) =± 0.17 at 298 K. 1 (k /k) =± 0.17 at 298 K. Comments on Preferred Values The preferred value of k is based on the results of Davidson et al. (1978) and the room temperature result of Force and Wiesenfeld (1981). The preferred value of the branching ratio k /k is the average of the values reported by Force and Wiesenfeld (1981) and by Takahashi et al. (1996). The preferred value of the branching ratio k /k was derived from the value reported by Takahashi et al. (1996), adjusted to make the sum of the two preferred branching ratios equal to unity. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4258 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Davidson, J. A., Schiff, H. I., Brown, T. J. and Howard, C. J.: J. Chem. Phys., 69, 4277, 1978. Force, A. P. and Wiesenfeld, J. R.: J. Phys. Chem., 85, 782, 1981. Takahashi, K., Wada, R., Matsumi, Y. and Kawasaki, M.: J. Phys. Chem., 100, 10145, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4259 IV.A2.84 O( D) + CFCl → ClO + CFCl (1) 3 2 → O( P) + CFCl (2) ◦ −1 1H (1) = -142 kJ·mol ◦ −1 1H (2) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (2.2± 0.7)× 10 173-343 Davidson et al., 1978 PLP (a) −10 (2.4± 0.2)× 10 298 Force and Wiesenfeld, 1981 PLP-RA Branching Ratios k /k = 0.13± 0.05 298 Force and Wiesenfeld, 1981 PLP-RA (b) k /k = 0.88± 0.18 298 Takahashi et al., 1996 PLP-LIF (c) Comments (a) Pulsed laser photolysis of O at 266 nm. O( D) atoms were monitored by time-resolved emission at 630 nm. 1 3 (b) O( D) atoms were monitored by resonance absorption at 130.4 nm and compared to O( P) atoms in the presence of ozone 3 1 in He diluent where the O( P) atom yield from the O( D) + O reaction is 1.0. (c) Branching ratio for ClO formation was determined by measurement of the LIF signal intensity of ClO normalized to that from O( D) + HCl. Preferred Values −10 3 −1 −1 k = 2.3× 10 cm molecule s independent of temperature over the range 170–350 K. k /k = 0.87 at 298 K. k /k = 0.13 at 298 K. Reliability 1 log k =± 0.1 over the temperature range 170–350 K. 1 (k /k) =± 0.13 at 298 K. 1 (k /k) =± 0.13 at 298 K. Comments on Preferred Values The preferred value of k is based on the results of Davidson et al. (1978) and the room temperature result of Force and Wiesenfeld (1981). The preferred value of the branching ratio k /k is the value reported by Force and Wiesenfeld (1981). The preferred value of the branching ratio k /k was derived from the value reported by Takahashi et al. (1996), adjusted to make the sum of the two preferred branching ratios equal to unity. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4260 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Davidson, J. A., Schiff, H. I., Brown, T. J. and Howard, C. J.: J. Chem. Phys., 69, 4277, 1978. Force, A. P. and Wiesenfeld, J. R.: J. Phys. Chem., 85, 782, 1981. Takahashi, K., Wada, R., Matsumi, Y. and Kawasaki, M.: J. Phys. Chem., 100, 10145, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4261 IV.A2.85 O( D) + CCl → ClO + CCl (1) 4 3 → O( P) + CCl (2) ◦ −1 1H (1) = -170 kJ·mol ◦ −1 1H (2) = -190 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (3.1± 0.9)× 10 203-343 Davidson et al., 1978 PLP (a) −10 (3.5± 0.3)× 10 298 Force and Wiesenfeld, 1981 PLP-RA Branching Ratios k /k = 0.14± 0.06 298 Force and Wiesenfeld, 1981 PLP-RA (b) k /k = 0.90± 0.19 298 Takahashi et al., 1996 PLP-LIF (c) Comments (a) Pulsed laser photolysis of O at 266 nm. O( D) atoms were monitored by time-resolved emission at 630 nm. 1 3 (b) O( D) atoms were monitored by resonance absorption at 130.4 nm and compared to O( P) atoms in the presence of ozone 3 1 in He diluent where the O( P) atom yield from the O( D) + O reaction is 1.0. (c) Branching ratio for ClO formation was determined by measurement of the LIF signal intensity of ClO normalized to that from O( D) + HCl. Preferred Values −10 3 −1 −1 k = 3.3× 10 cm molecule s independent of temperature over the range 200–350 K. k /k = 0.88 at 298 K. k /k = 0.12 at 298 K. Reliability 1 log k =± 0.1 over the temperature range 200–350 K. 1 (k /k) =± 0.12 at 298 K. 1 (k /k) =± 0.12 at 298 K. Comments on Preferred Values The preferred value of k is based on the results of Davidson et al. (1978) and the room temperature result of Force and Wiesenfeld (1981). The preferred values of the branching ratios were derived from the values reported by Force and Wiesenfeld (1981) (k /k) and by Takahashi et al. (1996) (k /k), with both reported values being reduced slightly to make the sum of the 2 1 two preferred branching ratios equal to unity. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4262 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Davidson, J. A., Schiff, H. I., Brown, T. J. and Howard, C. J.: J. Chem. Phys., 69, 4277, 1978. Force, A. P. and Wiesenfeld, J. R.: J. Phys. Chem., 85, 782, 1981. Takahashi, K., Wada, R., Matsumi, Y. and Kawasaki, M.: J. Phys. Chem., 100, 10145, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4263 IV.A2.86 1 3 O( D) + COFCl→ O( P) + COFCl ◦ −1 1H (1) = -190 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (3.7± 0.4)× 10 298 Fletcher and Husain, 1978 FP-RA (a) Comments (a) Flow system used, with O( D) atoms being monitored by time-resolved resonance absorption at 115 nm. The data analysis used a modiﬁed Beer-Lambert law. Preferred Values −10 3 −1 −1 k = 1.9× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.3 at 298 K. Comments on Preferred Values The preferred value is derived from the data of Fletcher and Husain (1978) by use of a scaling factor of 0.5. The weight of 1 1 evidence from many O( D) rate studies suggests that O( D) rates reported by Husain and co-workers contain a systematic error, and that these results can be made consistent with other O( D) recommended values in this evaluation by use of this scaling factor, as has been done in previous evaluations by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry and by the NASA Panel for Data Evaluation. See also the discussion of this topic in Davidson et al. (1978). References Davidson, J. A., Schiff, H. I., Brown, T. J. and Howard, C. J.: J. Chem. Phys., 69, 4277, 1978. Fletcher, I. S. and Husain, D.: J. Photochem. 8, 355, 1978. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4264 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.87 1 3 O( D) + COCl → O( P) + COCl (1) 2 2 → O( P) + Cl + CO (2) → other products (3) ◦ −1 1H (1) = -190 kJ·mol ◦ −1 1H (2) = -80 kJ·mol Rate coefﬁcient data (k = k + k + k ) 1 2 3 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 (2.6± 0.5)× 10 298 Chichinin, 1997 PLP-LMR −10 2.04× 10 exp[(27± 10)/T ] 194-429 Strekowski et al., 2000 PLP-RF −10 (2.22± 0.33)× 10 298 Branching Ratios (k + k )/k = 0.20± 0.04 194-429 Strekowski et al., 2000 PLP-RF (a) 1 2 Comments 1 3 3 (a) Branching ratio for conversion of O( D) to O( P), i.e. (k + k )/k was determined by comparison of the O( P) yield from 1 2 1 1 O( D) + COCl relative to that for O( D) + N . 2 2 Preferred Values −10 3 −1 −1 k = 2.2× 10 cm molecule s at 298 K. −10 3 −1 −1 k = 2.0× 10 exp(25/T ) cm molecule s over the temperature range 190-430 K. (k + k )/k = 0.20. 1 2 Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 25 K. 1 (k + k )/k =± 0.10 1 2 Comments on Preferred Values The preferred values of k are based on the results reported by Strekowski et al. (2000). The room temperature value reported by Chichinin et al. (1997) is 17% higher than the preferred value. The branching ratio (k + k )/k is taken from Strekowski 1 2 et al. (2000). Jayanty et al. (1976) present evidence, based on high yields of CO, that the reaction channel to produce ClO + ClCO is very important. References Chichinin, A. I.: J. Chem. Phys. 106, 1057, 1997. Jayanty, R. K. M., Simonaitis, R. and Heicklen, J.: J. Photochem., 5, 217, 1976. Strekowski, R. S., Nicovich, J. M. and Wine, P. H.: Chem. Phys. Lett. 330, 354, 2000. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4265 IV.A2.88 Cl + HC(O)Cl→ HCl + ClCO Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −13 7.9× 10 305 Sanhueza and Heicklen, 1975 RR (a) −13 (7.7± 1.0)× 10 298± 2 Niki et al., 1980 RR (b) −12 8.3× 10 exp(-705/T ) 266-321 Libuda et al., 1990 RR (c) −13 7.8× 10 298 −12 7.8× 10 exp(-720/T ) 222-296 Orlando, 1999 RR (d) −13 7.0× 10 298 Comments (a) Rate coefﬁcient ratios of k(Cl + HC(O)Cl)/k(Cl + CH Cl) = 1.85 ± 0.43 and k(Cl + HC(O)Cl)/k(Cl + CH Cl ) = 1.66 3 2 2 ± 0.15 derived from the kinetic analysis of HC(O)Cl in Cl atom-sensitized oxidation of CH Cl and CH Cl. This was 2 2 3 −13 3 −1 −1 placed on an absolute basis by use of k(Cl + CH Cl) = 5.3 × 10 cm molecule s and k(Cl + CH Cl ) = 3.6 × 3 2 2 −13 3 −1 −1 10 cm molecule s (IUPAC, current recommendation). The rate coefﬁcient cited in the table is the average of the two values obtained, which however differ signiﬁcantly. (b) Rate coefﬁcient ratio of k(Cl + HC(O)Cl)/k(Cl + CH Cl) = 1.6 ± 0.2 determined using FTIR absorption spectroscopy in irradiated Cl -CH Cl-O -N mixtures at 933 mbar total pressure. The rate coefﬁcient ratio was placed on an absolute 2 3 2 2 −13 3 −1 −1 basis by use of k(Cl + CH Cl) = 4.8× 10 cm molecule s (IUPAC, current recommendation). (c) Relative rate study. Cl atoms generated by the photolysis of Cl in Cl -HC(O)Cl-CH -N mixtures at 1000 mbar total 2 2 4 2 pressure. The concentrations of HC(O)Cl) and CH were measured by FTIR absorption spectroscopy (HC(O)Cl) and/or gas chromatography (CH ). Rate coefﬁcient ratios were determined over the temperature range 265.8–321.3 K, and −12 3 −1 −1 placed on an absolute basis by use of k(Cl + CH ) = 6.6 × 10 exp(-1240/T ) cm molecule s (IUPAC, current recommendation). (d) Temperature dependent rate coefﬁcient ratios of k(Cl + HC(O)Cl)/k(Cl + CH Cl ) were derived from the kinetic analysis 2 2 of HC(O)Cl in Cl atom-sensitized oxidation of CH Cl . Placed on an absolute basis by use of k(Cl + CH Cl ) = 5.9 × 2 2 2 2 −12 3 −1 −1 10 exp(-850/T ) cm molecule s (IUPAC, current recommendation). The value of k at 298 K was taken from the Arrhenius expression presented. Preferred Values −13 3 −1 −1 k = 7.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 8.1× 10 exp(-710/T ) cm molecule s over the temperature range 220-330 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 150 K. Comments on Preferred Values At 298 K, the rate coefﬁcients of Niki et al. (1980), Libuda et al. (1990), and Orlando (1999) are in good agreement, and form the basis of the recommendation at this temperature. The results of Sanhueza and Heicklen (1975) are also consistent with this www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4266 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry value. The recommended temperature dependence is based on the studies of Libuda et al. (1990) and Orlando (1999), which are in excellent agreement. The A-factor has been adjusted to reproduce the recommended value of k at 298 K. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Libuda, H. G., Zabel, F., Fink, E. H. and Becker, K. H.: J. Phys. Chem., 94, 5860, 1990. Niki, H., Maker, P. D., Savage, C. M. and Breitenbach, L. P.: Int. J. Chem. Kinet., 12, 915, 1980. Orlando, J. J.: Int. J. Chem. Kinet., 31, 515, 1999. Sanhueza, E. and Heicklen, J.: J. Phys. Chem., 79, 7, 1975. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4267 IV.A2.89 Cl + CH OCl → Cl + CH O (1) 3 2 3 → HCl + CH OCl (2) ◦ −1 1H (1) = -39.7 kJ·mol ◦ −1 1H (2) = -14.2 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 (6.0± 0.2)× 10 300 Kukui et al., 1997 DF-MS/LIF (a) Relative Rate Coefﬁcients −11 (6.3± 0.1)× 10 295 Carl et al., 1996 RR (b) Branching Ratios k /k = 0.8± 0.2 295 Carl et al., 1996 (c) k /k = 0.2± 0.1 295 k /k = 0.85± 0.06 300 Kukui et al., 1997 DF-MS/LIF (a) Comments (a) Flow tube operated at 2.5 – 3.5 mbar of He. Cl and Cl monitored as their parent ions, CH O was monitored by LIF, but 2 3 not quantiﬁed. The relative sensitivity of the MS to Cl and Cl was determined by titration of Cl to Cl via reaction with 2 2 NOCl. Rate coefﬁcients were obtained from the Cl decay in excess CH OCl, and the branching ratio, k /k, was derived 3 1 by numerical modeling of Cl loss and Cl production processes both in the desired reaction and secondary processes. (b) Relative rates of removal of CH OCl and C H (reference reactant) monitored by FTIR in air and N bath gas at total pres- 3 2 6 2 sure of 133 to 988 mbar. The value k/k(Cl + C H ) = 1.07± 0.02 was combined with the IUPAC (2007) recommendation 2 6 for k(Cl + C H ) to yield the value for k listed in the table. 2 6 (c) Branching ratios determined by quantitative analysis of CH OCl loss combined with HCl formation (FTIR experiments) and also by CH OCl loss combined with Cl formation (UV experiments). The chemistry was initiated by photolysis of 3 2 Cl or CH OCl itself. The HCl formation was modeled to assess the effects of secondary reactions such as Cl + HCHO. 2 3 Preferred Values −11 3 −1 −1 k = 6.1× 10 cm molecule s at 298 K. k /k = 0.85 at 298 K. k /k = 0.15 at 298 K. Reliability 1 log k =± 0.1 at 298 K. 1 (k /k) =± 0.1 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred values of k(298 K) is an average of the absolute and relative rate experiments, which are in excellent agreement. A consistent result for the branching ratios also emerges from these studies, and the value obtained by Kukui et al. (1997) for www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4268 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry k /k is adopted. The product analysis of Carl et al. (1996) provides conﬁrmation of this result, and that channel (2) provides the rest of the product formation. Theoretical work conﬁrms the existence of these two reaction channels, and suggests comparable effciencies at room temperature and dominance of hydrogen abstraction at higher temperatures (He et al., 2005). References Carl, S. A., Roehl, C. M., Muller ¨ , R., Moortgat, G. K. and Crowley, J. N.: J. Phys. Chem., 100, 17191, 1996. He, H.-Q., Liu, J.-Y., Li, Z.-S. and Sun, C.-C.: J. Comput. Chem., 26, 642, 2005. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Kukui, A., Roggenbuck, J. and Schindler, R. N.: Ber. Bunsenges. Phys. Chem., 101, 281, 1997. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4269 IV.A2.90 Cl + CH F→ HCl + CH F 3 2 ◦ −1 1H = -12.8 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 5.1× 10 exp[-(790± 45)/T ] 216-296 Manning and Kurylo, 1977 FP-RF (a) −13 3.6× 10 298 −13 (2.7± 0.2)× 10 298 Hitsuda et al., 2001 PLP-LIF (b) Relative Rate Coefﬁcients −11 1.3× 10 exp(-1050/T ) 273-368 Tschuikow-Roux et al., 1988 RR (c) −13 3.8× 10 298 −13 (3.4± 0.7)× 10 298 Tuazon et al., 1992 RR (d) −13 (3.24± 0.51)× 10 298 Wallington et al., 1992 RR (e) Comments (a) Cl atoms were formed by the photolysis of CCl . The Arrhenius expression was derived by least squares ﬁtting to tabulated data, excluding those in which CH F was excited by CO laser. 3 2 2 2 (b) Laser photolysis of HCl at 193 nm as Cl atom source. Both Cl( P ) and Cl( P ) were detected by VUV-LIF. 3/2 1/2 (c) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC. Derived values of A/A 2 CH4 −12 = (2.02 ± 0.01) and (E-E )/R = (-190 ± 6) K are placed on an absolute basis using k(Cl + CH ) = 6.6 × 10 CH4 4 3 −1 −1 exp(-1240/T ) cm molecule s (IUPAC, current recommendation). (d) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by −13 FT-IR spectroscopy. The measured rate coefﬁcient was placed on absolute basis by use of k(Cl + CH ) = 1.0 × 10 3 −1 −1 cm molecule s (IUPAC, current recommendation). (e) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by IR absorption. The measured rate coefﬁcient was placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH ) = −13 3 −1 −1 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −13 3 −1 −1 k = 3.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 4.0× 10 exp(-730/T ) cm molecule s over the temperature range 240-370 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 400 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4270 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The recommended value at 298 K is based on an average of all the data at this temperature excepting that of Hitsuda et al. (2001) which is lower than the others. The recommended expression for k is derived by least squares ﬁtting to the temperature dependent data set of Manning and Kurylo (1977), which covers the atmospherically most relevant temperature range, and the room temperature data of Tuazon et al. (1992) and Wallington et al. (1992). The rate coefﬁcients of Tschuikow-Roux et al. (1988) show good agreement in the common temperature range but a slightly greater temperature dependence. A steeper temperature dependence at high temperatures has also been observed in an unpublished experimental study covering 200 to 700 K, which was reported in the theoretical study of Rosenman and McKee (1997). References Hitsuda, K., Takahashi, K., Matsumi, Y. and Wallington, T. J.: J. Phys. Chem. A, 105, 5131, 2001. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Manning, R. G. and Kurylo, M. J.: J. Phys. Chem., 81, 291, 1977. Rosenman, E. and McKee, M. L.: J. Am. Chem. Soc., 119, 9033, 1997. Tschuikow-Roux, E., Faraji, F., Paddison, S., Niedzielski, J. and Miyokawa, K.: J. Phys. Chem., 92, 1488, 1988. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. Wallington, T. J., Ball, J. C., Nielsen, O. J. and Bartkiewicz, E.: J. Phys. Chem,. 96, 1241, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4271 IV.A2.91 Cl + CH Cl→ HCl + CH Cl 3 2 ◦ −1 1H = -14.3 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −10 2.1× 10 exp[(-1790± 70)/T ] 300-604 Clyne and Walker, 1973 DF-MS −13 5.4× 10 300 −11 3.4× 10 exp[(-1250± 60)/T ] 233-322 Manning and Kurylo, 1977 FP-RF −13 (5.10± 0.14)× 10 296 −13 (4.4± 0.6)× 10 298 Beichert et al., 1995 DF-RF −14 0.92 4.0× 10 T exp(-795/T ) 300-843 Bryukov et al., 2002 DF-MS −13 (5.2± 0.3)× 10 300 Relative Rate Coefﬁcients −13 (4.8± 0.4)× 10 295± 2 Wallington et al., 1990 RR (a) −13 (4.7± 0.6)× 10 298 Beichert et al., 1995 RR (b) −11 1.0× 10 exp[-(915± 120)/T ] 222-298 Orlando, 1999 RR (c) −13 4.7× 10 298 Comments (a) Cl atoms were generated from the photolysis of Cl in Cl -CH Cl-CH air mixtures at 930 mbar total pressure. The 2 2 3 4 concentrations of CH Cl and CH were monitored by FTIR absorption spectroscopy and a rate coefﬁcient ratio k(Cl + 3 4 −13 CH Cl)/k(Cl+CH ) = 4.79± 0.39 determined. This was placed on an absolute basis by use of k(Cl + CH ) = 1.0× 10 3 4 4 3 −1 −1 cm molecule s (IUPAC, current recommendation). (b) Cl atoms were generated from the photolysis of Cl in Cl -CH Cl-CH mixtures at atmospheric pressure of N , air or Ar. 2 2 3 4 2 The concentrations of CH Cl and CH were monitored by GC and a rate coefﬁcient ratio k(Cl + CH Cl)/k(Cl+CH ) = 3 4 3 4 −13 3 −1 4.65± 0.57 was determined. This was placed on an absolute basis by use of k(Cl + CH ) = 1.0× 10 cm molecule −1 s (IUPAC, current recommendation). (c) Cl atoms were generated from the photolysis of Cl in Cl -CH Cl-CH mixtures at 930 mbar total pressure of O -N . 2 2 3 4 2 2 The concentrations of CH Cl and CH were monitored by FTIR absorption spectroscopy and a temperature dependent 3 4 rate coefﬁcient ratio k(Cl + CH Cl)/k(Cl+CH ) determined. This was placed on an absolute basis by use of k(Cl + CH ) 3 4 4 −12 3 −1 −1 = 6.6 × 10 exp(-1240/T ) cm molecule s (IUPAC, current recommendation). The results were consistent with those obtained using CH Br as reference reactant. Preferred Values −13 3 −1 −1 k = 4.8× 10 cm molecule s at 298 K. −11 3 −1 −1 k = 2.3× 10 exp(-1150/T ) cm molecule s over the temperature range 220-360 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 200 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4272 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The results of all studies are in reasonable agreement at room temperature and below, though the data sets of Clyne and Walker (1973) and Bryukov et al. (2002) diverge signiﬁcantly at higher temperatures. The preferred 298 K rate coefﬁcient is the average of all studies at room temperature, excepting that of Clyne and Walker (1973). The temperature dependence was derived by least squares ﬁtting to the data of Manning and Kurylo (1977), Orlando (1999) and Bryukov et al. (2002) at temperatures below 360 K where these data sets are in very good agreement. References Beichert, P., Wingen, L., Lee, J., Vogt, R., Ezell, M. J., Ragains, M., Neavyn, R. and Finlayson-Pitts, B. J.: J. Phys. Chem., 99, 13156, 1995. Bryukov, M. G., Slagle, I. R. and Knyazev, D.: J. Phys. Chem., A, 106, 10532, 2002. Clyne, M. A. A. and Walker, R. F.: J. Chem. Soc. Faraday Trans., 1, 69, 1547, 1973. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Manning, R. G. and Kurylo, M. J.: J. Phys. Chem., 81, 291, 1977. Orlando, J. J.: Int. J. Chem. Kinet,. 31, 515, 1999. Wallington, T. J., Andino, J. M., Ball, J. C. and Japar, S. M.: J. Atmos. Chem., 10, 301, 1990. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4273 IV.A2.92 Cl + CH F → HCl + CHF 2 2 2 ◦ −1 1H = 0.5 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −11 1.0× 10 exp(-1470/T ) 281-368 Tschuikow-Roux et al., 1985 RR (a) −14 7.3× 10 298 −14 (3.2± 0.2)× 10 295 Nielsen et al., 1992 RR (b) Comments (a) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC. Derived values of A/A = 2 CH4 −12 (1.51 ± 0.06) and (E-E )/R = (228 ± 12) K were placed on an absolute basis using k(Cl + CH ) = 6.6 × 10 CH4 4 3 −1 −1 exp(-1240/T ) cm molecule s (IUPAC, current recommendation). (b) Photolysis of Cl in presence of CH F and CH in 920 mbar air or N bath gas. The value obtained, k/CH F )/k(CH ) 2 2 2 4 2 2 2 4 −13 3 −1 −1 = 0.32 ± 0.02 was placed on an absolute value using k(Cl + CH ) = 1.0 × 10 cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 5.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 7.0× 10 exp(-1470/T ) cm molecule s over the temperature range 280-370 K. Reliability 1 log k =± 0.5 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The recommended value at 298 K is an average of the two studies reported above. The temperature dependence is based on the study of Tschuikow-Roux et al. (1985), with the A-factor adjusted to reproduce the recommended value of k at 298 K. The large error limits in k and E/R reﬂect the poor agreement between these studies. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Nielsen, O. J., Ellermann, T., Bartkiewicz, E., Wallington, T. J. and Hurley, M. D.: Chem Phys. Lett., 192, 82, 1992. Tschuikow-Roux, E., Yano, T. and Niedzielski, J.: J. Chem. Phys., 82, 65, 1985. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4274 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.93 Cl + CH FCl→ HCl + CHFCl Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −11 1.2× 10 exp(-1230/T ) 273-368 Tschuikow-Roux et al., 1988 RR (a) −13 1.9× 10 298 −13 (1.10± 0.25)× 10 298 Tuazon et al., 1992 RR (b) Comments (a) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC, and the measured rate −12 coefﬁcient ratio was placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH ) = 9.6× 10 exp(-1240/T ) 3 −1 −1 cm molecule s (IUPAC, current recommendation). (b) Cl atoms were generated by photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient is placed on absolute basis by use of a rate coefﬁcient of k(Cl + CH ) = 1.0 −13 3 −1 −1 × 10 cm molecule s (IUPAC, current recommendation). Preferred Values −13 3 −1 −1 k = 1.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 7.0× 10 exp(-1230/T ) cm molecule s over the temperature range 270-370 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The recommended value is based on the room temperature results of Tuazon et al. (1992) and the temperature dependence reported by Tschuikow-Roux et al. (1988). References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Tschuikow-Roux, E., Faraji, F., Paddison, S., Niedzielski, J. and Miyokawa, K.: J. Phys. Chem., 92, 1488, 1988. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4275 IV.A2.94 Cl + CH Cl → HCl + CHCl 2 2 2 ◦ −1 1H = -19.9 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (5.5± 0.5)× 10 298 Davis et al., 1970 FP-RF −11 8.6× 10 exp[-(1450± 60)/T ] 298-621 Clyne and Walker, 1973 DF-MS −13 6.4× 10 298 −13 (3.2± 0.2)× 10 298 Beichert et al., 1995 DF-RF −16 1.58 1.48× 10 T exp(-360)/T ) 296-790 Bryukov et al., 2002 DF-RF −13 (3.5± 0.2)× 10 297 Relative Rate Coefﬁcients −13 (3.65± 0.39)× 10 298 Niki et al., 1980 RR (a) −11 1.9× 10 exp(-1190)/T ) 273-368 Tschuikow-Roux et al., 1988 RR (b) −13 3.5× 10 298 −13 (3.45± 0.18)× 10 298 Beichert et al., 1995 RR (c) −13 (3.51± 0.14)× 10 298 Catoire et al., 1996 RR (d) −12 4.4× 10 exp(-770)/T ) 222-298 Orlando, 1999 RR (e) −13 3.2× 10 Comments (a) Relative to Cl + CH Cl. Cl atoms were generated by the photolysis of Cl in the presence of CH Cl and CH Cl in air 3 2 2 2 3 at 930 mbar and the concentrations of CH Cl and CH measured by FTIR. The measured rate coefﬁcient ratio of k(Cl 2 2 4 −13 3 + CH Cl )/k(Cl + CH Cl) = (0.76 ± 0.08) was placed on an absolute basis using k(Cl + CH Cl) = 4.8 × 10 cm 2 2 3 3 −1 −1 molecule s (IUPAC, current recommendation). (b) Cl atoms were generated by the photolysis of Cl at 424 nm, and the concentrations of CH Cl and CH Cl measured by 2 2 2 3 GC. The measured rate coefﬁcient ratio of k(Cl + CH Cl )/k(Cl + CH ) = (2.81 ± 0.02) exp[-(49 ± 2)/T ] is placed on 2 2 4 −12 3 −1 −1 an absolute basis by using the rate coefﬁcient of k(Cl + CH ) = 6.6× 10 exp(-1240/T ) cm molecule s (IUPAC, current recommendation). (c) Cl atoms were generated from the photolysis of Cl in Cl -CH Cl -CH mixtures at atmospheric pressure of N , air or Ar. 2 2 2 2 4 2 The concentrations of CH Cl and CH were monitored by GC and a rate coefﬁcient ratio k(Cl + CH Cl )/k(Cl+CH ) = 3 4 2 2 4 −13 3 −1 3.45± 0.18 was determined. This was placed on an absolute basis by use of k(Cl + CH ) = 1.0× 10 cm molecule −1 s (IUPAC, current recommendation). (d) Cl atoms were generated from the photolysis of Cl in Cl -CH Cl -CH in air at 930 mbar total pressure. The relative 2 2 2 2 4 removal rates of CH Cl and CH were measured by FTIR. A rate coefﬁcient ratio k(Cl + CH Cl )/k(Cl+CH ) = 3.51± 2 2 4 2 2 4 −13 3 −1 −1 0.14 was obtained and placed on an absolute basis by use of k(Cl + CH ) = 1.0 × 10 cm molecule s (IUPAC, current recommendation). (e) Cl atoms were generated from the photolysis of Cl in Cl -CH Cl-CH mixtures at 930 mbar total pressure of O -N . 2 2 3 4 2 2 The concentrations of CH Cl and CH were monitored by FTIR absorption spectroscopy and a temperature dependent 3 4 rate coefﬁcient ratio k(Cl + CH Cl )/k(Cl+CH ) determined. This was placed on an absolute basis by use of k(Cl + CH ) 2 2 4 4 −12 3 −1 −1 = 6.6 × 10 exp(-1240/T ) cm molecule s (IUPAC, current recommendation). The results were consistent with those obtained using CH Br as reference reactant. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4276 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values −13 3 −1 −1 k = 3.4× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 5.9× 10 exp(-850/T ) cm molecule s over the temperature range 220-400 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values With the exception of the results of Davis et al. (1970) and Clyne and Walker (1973), the remaining 7 studies at room −13 3 −1 −1 temperature are consistent with a value of (3.4 ± 0.3) × 10 cm molecule s . Note, that for reaction with CH , both the room temperature rate coefﬁcients of Davis et al. (1970) and Clyne and Walker (1973) and the temperature dependence of Clyne and Walker (1973) are higher than recommended values, indicating possible systematic errors in these studies. The temperature dependent rate coefﬁcients of Orlando (1999) and Bryukov et al. (2002) are in good agreement at temperatures less than≈ 400 K. The preferred temperature dependence is taken from a least squares ﬁt to these two data sets between 400 and 220 K, and has been adjusted to reproduce the recommended value of k at 298 K. Curvature in the Arrhenius plot makes extrapolation beyond this temperature range problematic, hence use of the 3-parameter ﬁt of Bryukov et al. (2002) to cover temperatures up to 800 K. References Beichert, P., Wingen, L., Lee, J., Vogt, R., Ezell, M. J., Ragains, M., Neavyn, R. and Finlayson-Pitts, B. J.: J. Phys. Chem., 99, 13156, 1995. Bryukov, M. G., Slagle, I. R. and Knyazev, D.: J. Phys. Chem. A, 106, 10532, 2002. Catoire, V., Lesclaux, R., Schneider, W. F. and Wallington, T. J.: J. Phys. Chem., 100, 14356, 1996. Clyne, M. A. A. and Walker, R. F.: J. Chem. Soc. Faraday Trans., 1, 69, 1547, 1973. Davis, D. D., Braun, W. and Bass, A. M.: Int. J. Chem. Kinet., 2, 101, 1970. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Niki, H., Maker, P. D., Savage, C. M. and Breitenbach, L. P.: Int. J. Chem. Kinet., 12, 1001, 1980. Orlando, J. J.: Int. J. Chem. Kinet., 31, 515, 1999. Tschuikow-Roux, E., Faraji, F., Paddison, S., Niedzielski, J. and Miyokawa, K.: J. Phys. Chem., 92, 1488, 1988. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4277 IV.A2.95 Cl + CHF Cl→ HCl + CF Cl 2 2 ◦ −1 1H = -9.0 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 (1.7± 0.2)× 10 297 Sawerysyn et al., 1992 DF-MS −12 5.3× 10 exp[-(2430± 90)/T ] 298-430 Talhaoui et al., 1996 DF-MS −15 (1.4± 0.3)× 10 296 Relative Rate Coefﬁcients −15 (2.0± 0.4)× 10 298 Tuazon, et al., 1992 RR (a) Comments (a) Cl atoms were generated by photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient was placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH ) = −13 3 −1 −1 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 1.7× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 5.9× 10 exp(-2430/T ) cm molecule s over the temperature range 290-430 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The preferred value at 298 K is based on the absolute study of Talhaoui et al. (1996) and the relative rate measurement of Tuazon et al. (1992), which are in reasonable agreement. The work of Talhaoui et al. (1996) is assumed to supersede that of Sawerysyn et al. (1992). The recommended temperature dependence is based on the results of Talhaoui et al. (1996), with expanded error limits to reﬂect the fact that this is the only study of k(T). The A-factor has been adjusted to reproduce the value of k at 298 K. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Sawerysyn, J. P., Talhaoui, A., Meriaux, B. and Devolder, P.: Chem. Phys. Lett., 198, 197, 1992. Talhaoui, A., Louis, F., Meriaux, B., Devolder, P. and Sawerysyn, J. P.: J. Phys. Chem., 100, 2107, 1996. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4278 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.96 Cl + CHFCl → HCl + CFCl 2 2 ◦ −1 1H = -17.8 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 5.2× 10 exp[-(1675± 60)/T ] 298-430 Talhaoui et al., 1996 DF-MS −14 (1.9± 0.3)× 10 296 Relative Rate Coefﬁcients −14 (1.0± 0.2)× 10 294 Glavas and Heicklen, 1985 RR (a) −14 (2.1± 0.4)× 10 298 Tuazon et al., 1992 RR (b) Comments (a) Steady-state photolysis of Cl -CHFCl -O -NO-NO -N mixtures. The measured rate coefﬁcient ratio is placed on abso- 2 2 2 2 2 −31 6 −2 −1 lute basis by use of a rate coefﬁcient of k(Cl + NO + M) = 1.0× 10 cm molecule s . (a) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient was placed on absolute basis by use of a rate coefﬁcient of k(Cl + CH ) −13 3 −1 −1 = 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 2.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 5.5× 10 exp(-1675/T ) cm molecule s over the temperature range 290-430 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The preferred value at 298 K is based on the absolute study of Talhaoui et al. (1996) and the relative rate study of Tuazon et al. (1992). These results are preferred over the earlier, less direct results of Glavas and Heicklen (1985). The recommended temperature dependence is based on the results of Talhaoui et al. (1996), with expanded error limits to reﬂect the fact that this is the only study of k(T). The A-factor has been adjusted to reproduce the recommended value of k at 298 K. References Glavas, S. and Heicklen, J.: J. Photochem., 31, 21, 1985. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Talhaoui, A., Louis, F., Meriaux, B., Devolder, P. and Sawerysyn, J. P.: J. Phys. Chem., 100, 2107, 1996. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4279 IV.A2.97 Cl + CHCl → HCl + CCl 3 3 ◦ −1 1H = -39.2 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 1.45× 10 exp[-(1379± 44)/T ] 297-652 Clyne and Walker, 1973 DF-MS −13 (1.47± 0.35)× 10 297 −13 (3.7± 1.0)× 10 298 Jeoung et al., 1991 (a) −13 (1.1± 0.1)× 10 298 Beichert et al., 1995 DF-RF −12 8.0× 10 exp[-(1390± 80)/T ] 298-430 Talhaoui et al., 1996 DF-MS −14 (7.6± 1.3)× 10 298 −16 1.51 1.19× 10 T exp(-571/T ) 297-854 Bryukov et al., 2002 DF-RF −14 (8.9± 0.9)× 10 297 Relative Rate Coefﬁcients −12 1.9× 10 exp(-980/T ) 286-593 Knox, 1962 RR (b,c) −14 6.9× 10 298 −12 6.0× 10 exp(-1283/T ) 240-593 Knox, 1962 RR (b,d) −14 8.1× 10 298 −13 (1.13± 0.07)× 10 298 Beichert et al., 1995 RR (e) −13 (1.19± 0.13)× 10 298 Brahan et al., 1996 RR (f) −13 (1.1± 0.1)× 10 298 Catoire et al., 1996 RR (g) −12 2.5× 10 exp(-915/T ) 222-298 Orlando, 1999 RR (h) −13 1.15× 10 298 Comments (a) Very low pressure reactor with chemiluminescence and mass spectrometric detection. The reaction of Cl with CHCl was studied as part of a complex chemical system. (b) Cl atoms were generated by photolysis of Cl in Cl -CHCl -CH or Cl -CHCl -CH Cl mixtures. Organic reactants and 2 2 3 4 2 3 3 products monitored by GC. (c) Rate coefﬁcient ratio of k(Cl + CHCl )/k(Cl + CH ) = 0.286 exp(259/T ) was obtained and placed on an absolute basis by 3 4 −12 3 −1 −1 use of k(Cl + CH ) = 6.6× 10 exp(-1240/T ) cm molecule s (IUPAC, current recommendation). (d) Rate coefﬁcient ratio of k(Cl + CHCl )/k(Cl + CH Cl) = 0.26 exp(-133/T ) obtained, and placed on an absolute basis by 3 3 −11 3 −1 −1 use of k(Cl + CH Cl) = 2.3× 10 exp(-1150/T ) cm molecule s (IUPAC, current recommendation). (e) Cl atoms were generated from the photolysis of Cl in Cl -CHCl -CH mixtures at atmospheric pressure of N , air or Ar. 2 2 3 4 2 The concentrations of CHCl and CH were monitored by GC and a rate coefﬁcient ratio k(Cl + CHCl )/k(Cl+CH ) = 3 4 3 4 −13 3 −1 1.13± 0.07 was determined. This was placed on an absolute basis by use of k(Cl + CH ) = 1.0× 10 cm molecule −1 s (IUPAC, current recommendation). (f) Cl atoms were generated by photolysis of Cl in Cl -CHCl -CH or Cl -CHCl -CH Cl mixtures in an air or N bath gas 2 2 3 4 2 3 3 2 at 1023 mbar total pressure and 298 K. Rate coefﬁcient ratios k(Cl + CHCl )/k(Cl+CH ) and k(Cl + CHCl )/k(Cl+CH Cl) 3 4 3 3 −13 3 −1 −1 −13 were placed on an absolute basis by use of k(Cl + CH ) = 1.0× 10 cm molecule s and k(Cl + CH ) = 4.8× 10 4 4 3 −1 −1 cm molecule s (IUPAC, current recommendation). The value presented in the table is the average of experiments using both CH and CH Cl as reference reactants. 4 3 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4280 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry (g) Cl atoms were generated from the photolysis of Cl in Cl -CHCl -CH mixtures at 930 mbar total pressure of air. The 2 2 3 4 relative removal rates of CH Cl and CH were measured by FTIR. A rate coefﬁcient ratio k(Cl + CHCl )/k(Cl+CH ) 2 2 4 3 4 −13 3 −1 −1 = 1.1 ± 0.1 was obtained and placed on an absolute basis by use of k(Cl + CH ) = 1.0 × 10 cm molecule s (IUPAC, current recommendation). (h) Cl atoms were generated from the photolysis of Cl in Cl -CHCl -CH mixtures at 930 mbar total pressure of O -N . 2 2 3 4 2 2 The concentrations of CHCl and CH were monitored by FTIR absorption spectroscopy and a temperature dependent 3 4 rate coefﬁcient ratio k(Cl + CHCl )/k(Cl+CH ) determined. This was placed on an absolute basis by use of k(Cl + CH ) 3 4 4 −12 3 −1 −1 = 6.6 × 10 exp(-1240/T ) cm molecule s (IUPAC, current recommendation). The results were consistent with those obtained using CH Br as reference reactant Preferred Values −13 3 −1 −1 k = 1.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.4× 10 exp(-920/T ) cm molecule s over the temperature range 220-500 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The absolute rate constants of Beichert et al. (1995) and Bryukov et al. (2002), and the relative rate constants of Beichert et al. (1995), Brahan et al. (1996), Catoire et al. (1996) and Orlando (1999) are in good agreement. The 298 K recommendation is an average result from these studies. The temperature dependent data of Orlando (1999) and Bryukov et al. (2002) are reasonably well described by the expression for 220 K< T < 500 K given above, which has been adjusted to give the recommended value of k at 298 K. For extrapolation to higher temperatures, an expression of the form k = AT exp (E/RT ) as given by Bryukov et al (2002) is suitable. References Beichert, P., Wingen, L., Lee, J., Vogt, R., Ezell, M. J., Ragains, M., Neavyn, R. and Finlayson-Pitts, B. J.: J. Phys. Chem., 99, 13156, 1995. Brahan, K. M., Hewitt, A. D., Boone, G. D. and Hewitt, S. A: Int. J. Chem. Kinet., 28, 397, 1996. Bryukov, M. G., Slagle, I. R. and Knyazev, D.: J. Phys. Chem. A, 106, 10532, 2002. Catoire, V., Lesclaux, R., Schneider, W. F. and Wallington, T. J.: J. Phys. Chem., 100, 14356, 1996. Clyne, M. A. A. and Walker, R. F.: J. Chem. Soc. Faraday Trans., 1, 69, 1547, 1973. Davis, D. D., Braun, W. and Bass, A. M.: Int. J. Chem. Kinet., 2, 101, 1970. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeoung, S. C., Choo, K.Y. and Benson, S. W.: J. Phys. Chem., 95, 7282, 1991. Knox, J. H.: Trans. Faraday Soc., 58, 275, 1962. Niki, H., Maker, P. D., Savage, C. M. and Breitenbach, L. P., Int. J. Chem. Kinet., 12, 1001, 1980. Orlando, J. J.: Int. J. Chem. Kinet., 31, 515, 1999. Talhaoui, A., Louis, F., Meriaux, B., Devolder, P. and Sawerysyn, J. P.: J. Phys. Chem., 100, 2107, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4281 IV.A2.98 Cl + CH CH F → HCl + CH CHF (1) 3 2 3 → HCl + CH CH F (2) 2 2 ◦ −1 1H (1) = -9.6 kJ·mol ◦ −1 1H (2) = -5.3 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (6.8± 0.5)× 10 298 Hitsuda et al., 2001 PLP-LIF (a) Relative Rate Coefﬁcients −11 k = 1.0× 10 exp(-130/T ) 281-368 Tschuikow-Roux et al., 1985 RR (b) −12 k = 6.5× 10 298 −12 k = 8.3× 10 exp(-720/T ) 281-368 −13 k = 7.4× 10 298 Comments 2 2 (a) Laser photolysis of HCl at 193 nm as Cl atom source. Both Cl( P ) and Cl( P ) detected by VUV-LIF. 3/2 3/2 (b) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC and the measured rate −12 coefﬁcient ratios were placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH ) = 6.6× 10 exp(-1240/T ) 3 −1 −1 cm molecule s (IUPAC, current recommendation). Preferred Values −12 3 −1 −1 k = 6.5× 10 cm molecule s at 298 K. −11 3 −1 −1 k = 1.0× 10 exp(-130/T ) cm molecule s over the temperature range 280-370 K. −13 3 −1 −1 k = 7.4× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 8.3× 10 exp(-720/T ) cm molecule s over the temperature range 280-370 K. Reliability 1 log k = 1 log k =± 0.3 at 298 K. 1 2 1 (E /R) = 1 (E /R) =± 500 K. 1 2 Comments on Preferred Values The recommended values are based on the results of the relative rate study of Tschuikow-Roux et al. (1985). The overall rate constant k at room temperature, (k = k + k ), of Hitsuda et al. (2001) is consistent with this recommendation. 1 2 References Hitsuda, K., Takahashi, K., Matsumi, Y. and Wallington, T. J.: J. Phys. Chem. A, 105, 5131, 2001. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Tschuikow-Roux, E, Yano, T. and Niedzielski, J.: J. Chem. Phys., 82, 65, 1985. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4282 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.99 Cl + CH CHF → HCl + CH CF (1) 3 2 3 2 → HCl + CH CHF (2) 2 2 ◦ −1 1H (1) = -4.9 kJ·mol ◦ −1 1H (2) = 11.1 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −12 k = 7.0× 10 exp(-965/T ) 280-360 Yano and Tschuikow-Roux, 1986 RR (a) −13 k = 2.7× 10 298 −12 k = 7.8× 10 exp(-2399/T ) 280-360 −15 k = 2.5× 10 298 −13 (2.4± 0.7)× 10 295 Wallington and Hurley, 1992 RR (b) −13 (2.4± 0.5)× 10 298 Tuazon et al., 1992 RR (b) Comments (a) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC and the measured rate −11 coefﬁcient ratios were placed on an absolute basis by use of a rate coefﬁcient of k(Cl + C H ) = 8.3× 10 exp(-100/T ) 2 6 3 −1 −1 cm molecule s (IUPAC, current recommendation). (b) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic measured by FTIR spectroscopy. The measured rate coefﬁcient ratio is placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH ) −13 3 −1 −1 = 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −13 3 −1 −1 k = 2.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 6.3× 10 exp(-965/T ) cm molecule s over the temperature range 280-360 K. −15 3 −1 −1 k = 2.3× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 7.0× 10 exp(-2400/T ) cm molecule s over the temperature range 280-360 K. Reliability 1 log k =± 0.15 at 298 K. 1 log k =± 0.5 at 298 K. 1 (E /R) = 1 (E /R) =± 500 K. 1 2 Comments on Preferred Values The recommended value of the overall rate constant at room temperature is an average of all three relative rate studies, which show good agreement. The temperature dependence of k, k and k are taken from work of Yano and Tschuikow-Roux, (1986), 1 2 which supersedes their previous data (Tschuikow-Roux et al., 1985). References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Tschuikow-Roux, E., Yano, T. and Niedzielski, J.: J. Chem. Phys., 82, 65, 1985. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B: Int. J. Chem. Kinet.,24, 639, 1992. Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett., 189, 437, 1992. Yano, T. and Tschuikow-Roux, E.: J. Photochem., 32, 25, 1986. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4283 IV.A2.100 Cl + CH FCH F→ HCl + CHFCH F 2 2 2 ◦ −1 1H = -4.6 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −11 2.8× 10 exp[-(1065)/T ] 280-360 Yano and Tschuikow-Roux, 1986 RR (a) −13 7.8× 10 298 −13 (6.60± 0.16)× 10 298 Wallington et al., 1994 RR (b) −13 (6.53± 0.34)× 10 298 RR (c) Comments (a) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC and the measured rate −11 coefﬁcient ratios were placed on an absolute basis by use of a rate coefﬁcient of k(Cl + C H ) = 8.1× 10 exp(-100/T ) 2 6 3 −1 −1 cm molecule s (IUPAC, current recommendation). (b) Cl atoms were generated by the photolysis of Cl in presence of CH FCH F-CH in air at 930 mbar total pressure. Loss 2 2 2 4 of reactants was monitored by FTIR. The measured rate coefﬁcient ratio k(Cl + CH FCH F)/k(Cl + CH ) = (6.60± 0.16) 2 2 4 −13 3 −1 −1 was placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH ) = 1.0× 10 cm molecule s (IUPAC, current recommendation). (c) Cl atoms were generated by the photolysis of Cl in presence of CH FCH F-CH Cl mixtures in air at 930 mbar total 2 2 2 3 pressure. Loss of reactants was monitored by FTIR. The measured rate coefﬁcient ratio k(Cl + CH FCH F)/k(Cl + 2 2 −13 3 CH Cl) = (1.36± 0.07) was placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH Cl) = 4.8× 10 cm 3 3 −1 −1 molecule s (IUPAC, current recommendation). Preferred Values −13 3 −1 −1 k = 7.0× 10 cm molecule s at 298 K. −11 3 −1 −1 k = 2.5× 10 exp(-1065/T ) cm molecule s over the temperature range 280-360 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The recommended value at 298 K is an average of the rate constants obtained by the relative rate studies of Yano and Tschuikow-Roux (1986) and Wallington et al. (1994). The expression for the temperature dependence is taken from Yano and Tschuikow-Roux (1986), modiﬁed to reproduce the recommended value at 298 K. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Wallington, T. J., Hurley, M. D., Ball, J. C., Ellermann, T., Nielsen, O. J. and Sehested, J.: J. Phys. Chem., 98, 5435, 1994. Yano, T. and Tschuikow-Roux, E.: J. Photochem., 32, 25, 1986. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4284 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.101 Cl + CH CF → HCl + CH CF 3 3 2 3 ◦ −1 1H = 18.0 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 < 1× 10 298 Hitsuda et al., 2001 PLP-LIF (a) Relative Rate Coefﬁcients −12 6.9× 10 exp(-3720/T ) 281-368 Tschuikow-Roux et al., 1985 RR (b) −17 2.6× 10 298 Comments 2 2 (a) Laser photolysis of HCl at 193 nm as Cl atom source. Both Cl( P ) and Cl( P ) detected by VUV-LIF. 3/2 1/2 (b) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC and the measured rate −12 coefﬁcient ratio is placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH ) = 6.6 × 10 exp(-1240/T ) 3 −1 −1 cm molecule s (IUPAC, current recommendation). Preferred Values −17 3 −1 −1 k = 2.6× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 6.9× 10 exp(-3720/T ) cm molecule s over the temperature range 280-370 K. Reliability 1 log k =± 0.5 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The recommended value is based on the results of the relative rate study of Tschuikow-Roux et al., (1985). The room temper- ature upper limit to k of Hitsuda et al. (2001) is consistent with this. References Hitsuda, K., Takahashi, K., Matsumi, Y. and Wallington, T. J.: J. Phys. Chem. A, 105, 5131, 2001. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Tschuikow-Roux, E., Yano, T. and Niedzielski, J.: J. Chem. Phys., 82, 65, 1985. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4285 IV.A2.102 Cl + CH FCHF → HCl + CH FCF (1) 2 2 2 2 → HCl + CHFCHF (2) ◦ −1 1H (1) = 2.2 kJ·mol ◦ −1 1H (2) = 0.0 kJ·mol Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −12 k = 3.3× 10 exp(-1450/T ) 281-368 Tschuikow-Roux et al., 1985 RR (a) −14 k = 2.5× 10 298 −12 k = 4.6× 10 exp(-1560/T ) 281-368 −14 k = 2.5× 10 298 Comments (a) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC and the measured rate −12 coefﬁcient ratios were placed on an absolute basis by use of a rate coefﬁcient of k(Cl + CH ) = 6.6× 10 exp(-1240/T ) 3 −1 −1 cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 2.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 3.3× 10 exp(-1450/T ) cm molecule s over the temperature range 280-370 K. −14 3 −1 −1 k = 2.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 4.6× 10 exp(-1560/T ) cm molecule s over the temperature range 280-370 K. Reliability 1 log k = 1 log k =± 0.5 at 298 K. 1 2 1 (E/R) = 1 (E/R) =± 500 K. 1 2 Comments on Preferred Values The recommended values are based on the results of the single determination of this rate constant by Tschuikow-Roux et al. (1985). References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Tschuikow-Roux, E., Yano, T. and Niedzielski, J.: J. Chem. Phys., 82, 65, 1985. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4286 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.103 Cl + CH CF Cl→ HCl + CH CF Cl 3 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −16 (5.6± 2.0)× 10 297 Sawerysyn et al., 1992 DF-MS −15 <4.4× 10 298 Warren and Ravishankara, 1993 PLP-RF −12 1.5× 10 exp[-(2420± 400)/T ] 296-438 Talhaoui et al., 1996 DF-MS −16 (4.7± 1.3)× 10 296 Relative Rate Coefﬁcients −16 (3.90± 0.52)× 10 295 Wallington and Hurley, 1992 RR (a) −16 (3.7± 0.8)× 10 298 Tuazon et al., 1992 RR (a) Comments (a) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio is placed on an absolute basis by use of a rate coefﬁcient of k(Cl −13 3 −1 −1 + CH ) = 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −16 3 −1 −1 k = 4.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.4× 10 exp(-2420/T ) cm molecule s over the temperature range 296-440 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The preferred value of the rate constant at 298 K is based on the results reported by Wallington and Hurley (1992), Tuazon et al. (1992) and Talhaoui et al. (1996). The latter study supersedes the work of Sawerysyn et al. (1992). The single temperature dependent study of Talhaoui et al. (1996) forms the basis for the recommendation of k(T), with the A-factor adjusted to reproduce the recommended value of k at 298 K. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Sawerysyn, J. P., Talhaoui, A., Meriaux, B. and Devolder, P.: Chem. Phys. Lett., 198, 197, 1992. Talhaoui, A., Devolder, L. P., Meriaux, B., Sawerysyn, J.-P., Rayez, M.-T. and Rayez, J.-C.: J. Phys. Chem., 100, 13531, 1996. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett., 189, 437, 1992. Warren, R. F. and Ravishankara, A. R.: Int. J. Chem. Kinet., 25, 833, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4287 IV.A2.104 Cl + CH CFCl → HCl + CH CFCl 3 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 (2.1± 0.2)× 10 297 Sawerysyn et al., 1992 DF-MS −12 1.0× 10 exp[-(1800± 500)/T ] 298-376 Warren and Ravishankara, 1993 PLP-RF −15 (2.4± 0.4)× 10 298 −12 3.0× 10 exp[-(2220± 150)/T ] 299-429 Talhaoui et al., 1996 DF-MS −15 (1.7± 0.2)× 10 299 Relative Rate Coefﬁcients −15 (2.0± 0.2)× 10 295 Wallington and Hurley, 1992 RR (a) −15 (2.4± 0.5)× 10 298 Tuazon et al., 1992 RR (a) Comments (a) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio was placed on an absolute basis by use of a rate coefﬁcient of k(Cl −13 3 −1 −1 + CH ) = 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 2.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.7× 10 exp(-2000/T ) cm molecule s over the temperature range 290-380 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The preferred value at 298 K is an average of the results reported by Wallington and Hurley (1992), Tuazon et al. (1992), Warren and Ravishankara (1993) and Talhaoui et al. (1996). The expression for the temperature dependence is an average of the values of E/R obtained by Warren and Ravishankara (1992) and Talhaoui et al. (1996). The data in Sawerysyn et al. (1992) are superseded by those in Talhaoui et al. (1996). References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Sawerysyn, J. P., Talhaoui, A., Meriaux, B. and Devolder, P.: Chem. Phys. Lett., 198, 197, 1992. Talhaoui, A., Devolder, L. P., Meriaux, B., Sawerysyn, J.-P., Rayez, M.-T. and Rayez, J.-C.: J. Phys. Chem., 100, 13531, 1996. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B: Int. J. Chem. Kinet., 24, 639, 1992. Wallington, T.J. and Hurley, M. D.: Chem. Phys. Lett., 189, 437, 1992. Warren, R. F. and Ravishankara, A. R.: Int. J. Chem. Kinet., 25, 833, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4288 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.105 Cl + CH CCl → HCl + CH CCl 3 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 < 2.40× 10 259 Wine et al., 1982 PLP-RF −14 < 3.68× 10 298 −14 < 7.74× 10 356 −12 2.8× 10 exp[-(1790± 320)/T ] 298-418 Talhaoui et al., 1996 DF-MS −15 (7.1± 1.1)× 10 298 Relative Rate Coefﬁcients −15 (9.9± 2.0)× 10 296 Platz et al., 1995 RR (a) Comments (a) Photolysis of Cl -CH CCl -CD mixtures in air or N at 930 mbar total pressure, with the loss of reactants monitored by 2 3 3 4 2 FTIR. A value of k(Cl + CH CCl )/k(Cl + CD ) = (1.62± 0.05) was obtained and placed on an absolute basis using k(Cl 3 3 4 −15 3 −1 −1 + CD ) = 6.1× 10 cm molecule s (Wallington and Hurley, 1992). Preferred Values −15 3 −1 −1 k = 7× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.8× 10 exp(-1790/T ) cm molecule s over the temperature range 290-420 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The preferred values of k are based on the direct study of Talhaoui et al. (1996), which is consistent with the upper limits of Wine et al. (1982) and with the room temperature relative rate study of Platz et al. (1995). References Platz, J., Nielsen, O. J., Sehested, J. and Wallington, T. J.: J. Phys. Chem., 99, 6570, 1995. Talhaoui, A., Devolder, L. P., Meriaux, B., Sawerysyn, J.-P., Rayez, M.-T. and Rayez, J.-C.: J. Phys. Chem., 100, 13531, 1996. Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett., 189, 437, 1992. Wine, P. H., Semmes, D. H. and Ravishankara, A. R.: Chem. Phys. Lett., 90, 128, 1982. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4289 IV.A2.106 Cl + CH FCF → HCl + CHFCF 2 3 3 ◦ −1 1H = 1.8 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 (1.6± 0.3)× 10 297 Sawerysyn et al., 1992 DF-MS −12 3.2× 10 exp[-(2300± 70)/T ] 298-423 Louis et al., 1997 DF-MS −15 (1.4± 0.3)× 10 298 Relative Rate Coefﬁcients −15 (1.38± 0.18)× 10 295 Wallington and Hurley, 1992 RR (a) −15 (1.6± 0.3)× 10 298 Tuazon et al., 1992 RR (a) Comments (a) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio was placed on an absolute basis by use of a rate coefﬁcient of k(Cl −13 3 −1 −1 + CH ) = 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 1.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 3.4× 10 exp(-2300/T ) cm molecule s over the temperature range 298-430 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The preferred value at 298 K is based on the results reported by Louis et al. (1997), Wallington and Hurley (1992) and Tuazon et al. (1992) which are in good agreement. The room temperature rate constant of Sawerysyn et al. (1992) is considered to be superseded by that measured in the same group by Louis et al. (1997). The temperature dependence of k is taken from Louis et al. (1997) with the A-factor adjusted to reproduce the recommended value of k at 298 K. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Louis, J., Talhaoui, A., Sawerysyn, J. P., Rayez, M.-T. and Rayez, J.-C.: J. Phys. Chem. A,. 101, 8503, 1997. Sawerysyn, J. P., Talhaoui, A., Meriaux, B. and Devolder, P.: Chem. Phys. Lett., 198, 197, 1992. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett., 189, 437, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4290 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.107 Cl + CHF CHF → HCl + CF CHF 2 2 2 2 ◦ −1 1H = 6.5 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −12 8.9× 10 exp(-2444/T ) 280-360 Yano and Tschuikow-Roux, 1986 RR (a) −15 2.4× 10 298 −15 1.9× 10 298 Nielsen et al., 1992 RR (b) Comments (a) Cl atoms were generated by the photolysis of Cl . Product yield ratios were measured by GC. The measured rate coef- −11 3 −1 −1 ﬁcient ratio was placed on an absolute basis by use of k(Cl + C H ) = 8.3 × 10 exp(-100/T ) cm molecule s 2 6 (IUPAC, current recommendation). (b) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio was placed on an absolute basis by use of k(Cl + CH ) = 1.0 × −13 3 −1 −1 10 cm molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 2.2× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 7.9× 10 exp(-2440/T ) cm molecule s over the temperature range 280-360 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The recommended value at 298 K is an average of the results of Nielsen et al. (1992) and Yano and Tschuikow-Roux (1986). The expression for the temperature dependence is that of Yano and Tschuikow-Roux (1986), with the A-factor modiﬁed to reproduce the recommended value of k at 298 K. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Nielsen, O. J., Ellermann, T., Sehested, J. and Wallington, T. J.: J. Phys. Chem., 96, 10875, 1992. Yano, T. and Tschuikow-Roux, E.: J. Photochem., 32, 25, 1986. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4291 IV.A2.108 Cl + CHF CF → HCl + CF CF 2 3 2 3 ◦ −1 1H = 10.7 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −16 (2.4± 0.5)× 10 298 Tuazon et al., 1992 RR (a) −16 (2.6± 0.6)× 10 295 Sehested et al., 1993 RR (b) Comments (a) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient was placed on an absolute basis by use of a rate coefﬁcient of k(Cl + −13 3 −1 −1 CH ) = 1.0× 10 cm molecule s (IUPAC, current recommendation). (b) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient was ratio placed on an absolute basis by use of a rate coefﬁcient of k(Cl −16 3 −1 −1 + CH CF Cl) = 4.1× 10 cm molecule s (IUPAC, current recommendation). 3 2 Preferred Values −16 3 −1 −1 k = 2.5× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.2 at 298 K. Comments on Preferred Values The preferred value at 298 K is based on the results of the relative rate studies of Tuazon et al. (1992) and Sehested et al. (1993), which are in good agreement. Since studies have only been carried out at room temperature, no temperature dependence is recommended. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Sehested, J., Ellermann, T., Nielsen, O. J., Wallington, T. J. and Hurley, M. D.: Int. J. Chem. Kinet., 25, 701, 1993. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4292 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.109 Cl + CHFClCF → HCl + CFClCF 3 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 1.16× 10 exp[-(1800± 150)/T ] 276-376 Warren and Ravishankara, 1993 PLP-RF −15 (2.62± 0.50)× 10 298 Relative Rate Coefﬁcients −15 (2.7± 0.6)× 10 298 Tuazon et al. 1992 RR (a) Comments (a) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio was placed on an absolute basis by use of a rate coefﬁcient of k(Cl −13 3 −1 −1 + CH ) = 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 2.7× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.1× 10 exp(-1800/T ) cm molecule s over the temperature range 270-380 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The preferred value at 298 K is based on the results reported by Warren and Ravishankara (1993) and Tuazon et al. (1992), which are in good agreement. The recommended temperature dependence is that reported by Warren and Ravishankara (1993), the only study carried out over a range of temperatures. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. Warren, R. F. and Ravishankara, A. R.: Int. J. Chem. Kinet., 25, 833, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4293 IV.A2.110 Cl + CHCl CF → HCl + CCl CF 2 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 3.94× 10 exp[-(1740± 100)/T ] 276-382 Warren and Ravishankara, 1993 PLP-RF −14 (1.15± 0.30)× 10 298 Relative Rate Coefﬁcients −14 (1.22± 0.18)× 10 295 Wallington and Hurley, 1992 RR (a) −14 (1.4± 0.3)× 10 298 Tuazon et al. 1992 RR (a) Comments (a) Cl atoms were generated by the photolysis of Cl . The decays of the reactant and reference organic were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio was placed on an absolute basis by use of a rate coefﬁcient of k(Cl −13 3 −1 −1 + CH ) = 1.0× 10 cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 4.4× 10 exp(-1740/T ) cm molecule s over the temperature range 270-380 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The preferred value at 298 K is based on the results reported by Warren and Ravishankara (1993), Wallington and Hurley (1992), and Tuazon et al. (1992), which are in good agreement. The recommended temperature dependence is that reported by Warren and Ravishankara, (1993) the only study carried out over a range of temperatures. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Tuazon, E. C., Atkinson, R. and Corchnoy, S. B.: Int. J. Chem. Kinet., 24, 639, 1992. Wallington, T. J. and Hurley, M. D.: Chem. Phys. Lett., 189, 437, 1992. Warren, R. F. and Ravishankara, A. R.: Int. J. Chem. Kinet., 25, 833, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4294 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.111 HO + CH Cl→ H O + CH Cl 3 2 2 ◦ −1 1H = -79.8 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (3.6± 0.8)× 10 296± 2 Howard and Evenson, 1976 DF-LMR −12 4.1× 10 exp[-(1359± 151)/T ] 298-423 Perry et al., 1976 FP-RF −14 (4.4± 0.5)× 10 298 −12 1.84× 10 exp[-(1098± 36)/T ] 250-350 Davis et al., 1976 FP-RF −14 (4.29± 0.21)× 10 298 −14 (4.10± 0.69)× 10 297 Paraskevopoulos et al., 1981 FP-RA −21 3.08 2.21× 10 T exp[-(232± 423)/T ] 247-483 Jeong and Kaufman, 1982; DF-RF −14 (3.95± 0.26)× 10 293 Jeong et al., 1984 −14 (5.3± 0.8)× 10 298 Brown et al., 1990 DF-RF −14 0.89 2.90× 10 T exp[-(1447± 75)/T ] 295-955 Taylor et al., 1993 PLP-LIF (a) −14 (4.9± 0.6)× 10 295 −13 0.5 1.24× 10 T exp[-(1210± 52)/T ] 224-398 Herndon et al., 2001 PLP-LIF −14 (3.32± 0.10)× 10 298 Relative Rate Coefﬁcients −14 7.8× 10 298 Cox et al., 1976 RR (b) −18 2 5.35× 10 T exp[-(775± 74)/T ] 293-358 Hsu and DeMore, 1994 RR (c) −14 3.53× 10 298 Comments (a) These data supersede the earlier data from this group (Taylor et al., 1989). (b) HO radicals were generated by the photolysis of HONO-air mixtures at one atmosphere total pressure. Relative rate coefﬁcients were obtained from measurements of the rates of NO formation as a function of the HONO and organic concentrations. Based on the effect of CH Cl on NO formation and a rate coefﬁcient for the reaction of HO radicals with −15 3 −1 −1 CH of 6.4 × 10 cm molecule s at 298 K (IUPAC, current recommendation), the rate coefﬁcient cited in the table is obtained. (c) HO radicals were generated by the UV photolysis of O in the presence of water vapor. The concentrations of CH Cl 3 3 and CH CHF were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CH Cl)/k(HO + 3 2 3 CH CHF ) = (1.91 ± 0.45) exp[-(195 ± 74)/T ] is placed on an absolute base by using a rate coefﬁcient of k(HO + 3 2 −18 2 3 −1 −1 CH CHF ) = 2.80× 10 T exp(-580/T ) cm molecule s (IUPAC, current recommendation). 3 2 Preferred Values −14 3 −1 −1 k = 3.6× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.1× 10 exp(-1210/T ) cm molecule s over the temperature range 220-300 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 200 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4295 Comments on Preferred Values At room temperature, the absolute rate coefﬁcients of Herndon et al. (2001) are signiﬁcantly lower than those from the earlier studies of Perry et al (1976), Davis et al. (1976), Cox et al. (1976), Paraskevopoulos et al. (1981), Jeong and Kaufman (1982), Brown et al. (1990) and Taylor et al. (1993), but are in good agreement with the absolute rate coefﬁcient of Howard and Evenson (1976) and the relative rate coefﬁcients of Hsu and DeMore (1994). Furthermore, the relative rate coefﬁcients of Hsu and DeMore (1994) are in excellent agreement with the absolute rate coefﬁcients of Herndon et al. (2001) over the temperature range common to both studies (293–358 K), and at 363 and 401 K the rate coefﬁcients of Jeong and Kaufman (1982) are in good agreement with the data of Herndon et al. (2001). The absolute rate coefﬁcients of Herndon et al. (2001) have been 2 −18 2 3 −1 ﬁtted to the three parameter equation k = CT exp(-D/T ), resulting in k = 4.34 × 10 T exp(-700/T ) cm molecule −1 s over the temperature range 224–398 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range 2 2 temperature, T , of 255 K and is obtained from the three parameter equation with A = C e T and B = D + 2T . As noted m m above, the rate coefﬁcients obtained from the relative rate study of Hsu and DeMore (1994) are in excellent agreement with the preferred values. 12 13 Gola et al. (2005) have measured a rate coefﬁcient ratio of k(HO + CH Cl)/k(HO + CH Cl) = 1.059± 0.008 at 298± 3 3 2 K, and the deuterium isotope effect for the reaction of HO radicals with CD Cl, of k(HO + CH Cl)/k(HO + CD Cl) = 3.9± 3 3 3 0.4 at 298± 2 K. References Brown, A. C., Canosa-Mas, C. E. and Wayne, R. P.: Atmos. Environ., 24A, 361, 1990. Cox, R. A., Derwent, R. G., Eggleton, A. E. J. and Lovelock, J. E.: Atmos. Environ., 10, 305, 1976. Davis, D. D., Machado, G., Conaway, B., Oh, Y. and Watson, R. T.: J. Chem. Phys., 65, 1268, 1976. Gola, A. A., D’Anna, B., Feilberg, F. L., Sellevag, ˚ S. R., Bache-Andreassen, L. and Nielsen, C. J.: Atmos. Chem. Phys., 5, 2395, 2005. Herndon, S. C., Gierczak, T., Talukdar, R. K. and Ravishankara, A. R.: Phys. Chem. Chem. Phys., 3, 4529, 2001. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. Hsu, K.-J. and DeMore, W. B.: Geophys. Res. Lett., 21, 805, 1994. IUPAC: http://www,iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem., 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem., 88, 1222, 1984. Paraskevopoulos, G., Singleton, D. L. and Irwin, R. S.: J. Phys. Chem., 85, 561, 1981. Perry, R. A., Atkinson, R. and Pitts, J. N. Jr.: J. Chem. Phys., 64, 1618, 1976. Taylor, P. H., Jiang, Z. and Dellinger, B.: Int. J. Chem. Kinet., 25, 9, 1993. Taylor, P. H., D’Angelo, J. A., Martin, M. C., Kasner, J. H. and Dellinger, B.: Int. J. Chem. Kinet., 21, 829, 1989. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4296 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.112 HO + CH FCl→ H O + CHFCl 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (3.7± 0.6)× 10 296± 2 Howard and Evenson, 1976 DF-LMR −12 2.84× 10 exp[-(1259± 50)/T ] 245-375 Watson et al., 1977 FP-RF −14 (4.21± 0.41)× 10 298 −12 3.1× 10 exp[-(1320± 100)/T ] 273-373 Handwerk and Zellner, 1978 FP-RA −14 (3.5± 0.7)× 10 293 −14 (4.45± 0.67)× 10 297 Paraskevopoulos et al., 1981 FP-RA −19 2.41 1.57× 10 T exp[-(307± 382)/T ] 250-486 Jeong and Kaufman, 1982; DF-RF −14 (4.94± 0.30)× 10 295 Jeong et al., 1984 Relative Rate Coefﬁcients −12 1.46× 10 exp[-(1076± 24)/T ] 293-371 DeMore, 1996 RR (a) −14 3.95× 10 298 Comments (a) HO radicals were generated by the photolysis of O at 254 nm in the presence of H O, and CH Cl was used as the 3 2 2 2 reference compound. CH FCl and CH Cl were monitored by FTIR spectroscopy, and a rate coefﬁcient ratio of k(HO + 2 2 2 CH FCl)/k(HO + CH Cl ) = 0.81 exp[-(216± 24)/T ] was determined. This rate coefﬁcient ratio is placed on an absolute 2 2 2 −12 3 −1 −1 basis by use of a rate coefﬁcient of k(HO + CH Cl ) = 1.8 × 10 exp(-860/T ) cm molecule s (IUPAC, current 2 2 recommendation). Preferred Values −14 3 −1 −1 k = 3.9× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.6× 10 exp(-1105/T ) cm molecule s over the temperature range 240-300 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The absolute rate coefﬁcients of Jeong and Kaufman (1982) are signiﬁcantly higher than the absolute and relative rate data of Howard and Evenson (1976), Watson et al. (1977), Handwerk and Zellner, 1978), Paraskevopoulos et al. (1981) and DeMore (1996), with the discrepancies being more marked at the lowest temperatures studied by Jeong and Kaufman (250 and 295 K). The rate coefﬁcients measured by Howard and Evenson (1976), Watson et al. (1977), Handwerk and Zellner (1978), Paraskevopoulos et al. (1981) and DeMore (1996) are in reasonably good agreement, and the rate coefﬁcients from 2 −18 2 these studies have been ﬁtted to the three parameter expression k = CT exp(-D/T ), resulting in k = 3.03 × 10 T exp(- 3 −1 −1 574/T ) cm molecule s over the temperature range 245–375 K. The preferred Arrhenius expression, k = A exp(-B/T ), is 2 2 centered on a mid-range temperature, T , of 265 K and is obtained from the three parameter equation with A = Ce T and B = D+ 2T . Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4297 References DeMore, W. B.: J. Phys. Chem., 100, 5813, 1996. Handwerk, V. and Zellner, R.: Ber. Bunsenges. Phys. Chem., 82, 1161, 1978. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem., 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem., 88, 1222, 1984. Paraskevopoulos, G., Singleton, D. L. and Irwin, R. S.: J. Phys. Chem., 85, 561, 1981. Watson, R. T., Machado, G., Conaway, B., Wagner, S. and Davis, D. D.: J. Phys. Chem., 81, 256, 1977. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4298 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.113 HO + CH Cl → H O + CHCl 2 2 2 2 ◦ −1 1H = -94.6 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (1.55± 0.34)× 10 296± 2 Howard and Evenson, 1976 DF-LMR −13 (1.45± 0.20)× 10 298.5 Perry et al., 1976 FP-RF −12 4.27× 10 exp[-(1094± 82)/T ] 245-375 Davis et al., 1976 FP-RF −13 (1.16± 0.05)× 10 298 −19 2.54 1.61× 10 T exp[-(186± 493)/T ] 251-455 Jeong and Kaufman, 1982; DF-RF −13 (1.53± 0.095)× 10 292 Jeong et al., 1984 −15 1.09 4.01× 10 T exp[-(771± 48)/T ] 295-955 Taylor et al., 1993 PLP-LIF (a) −13 (1.47± 0.18)× 10 295 −12 2.61× 10 exp[-(944± 29)/T ] 277-370 Villenave et al., 1997 FP-RF −13 (1.10± 0.05)× 10 298 −13 0.5 6.6× 10 T exp[-(721± 32)/T ] 219-394 Herndon et al., 2001 PLP-LIF −13 (1.00± 0.14)× 10 298 Relative Rate Coefﬁcients −14 9.5× 10 298 Cox et al., 1976 RR (b) −18 2 2.72× 10 T exp[-(286± 29)/T ] 293-360 Hsu and DeMore, 1994 RR (c,d) −14 9.25× 10 298 −18 2 1.96× 10 T exp[-(104± 20)/T ] 298-368 Hsu and DeMore, 1994 RR (c,e) −13 1.22× 10 298 Comments (a) These data supersede the earlier data from this group (Taylor et al., 1989). (b) HO radicals were generated by the photolysis of HONO-air mixtures at 1.013 bar pressure. Relative rate coefﬁcients were obtained from measurements of the rates of NO formation as a function of the HONO and organic concentrations. Based −15 on the effect of CH Cl on NO formation and a rate coefﬁcient for the reaction of HO radicals with CH of 6.4× 10 2 2 4 3 −1 −1 cm molecule s at 298 K (IUPAC, current recommendation), the rate coefﬁcient cited in the table is obtained. (c) HO radicals were generated by the UV photolysis of O in the presence of water vapor. CH Cl and CH CHF 3 2 2 3 2 (or CH CH F) concentrations were measured by FTIR spectroscopy. The measured rate coefﬁcient ratios of k(HO + 3 2 CH Cl )/k(HO + CH CHF ) = (0.97 ± 0.09) exp[(294 ± 29)/T ] and k(HO + CH Cl )/k(HO + CH CH F) = (0.32 ± 2 2 3 2 2 2 3 2 −18 0.02) exp[(171± 20)/T ] are placed on an absolute basis by using rate coefﬁcients of k(HO + CH CHF ) = 2.80× 10 3 2 2 3 −1 −1 −18 2 T exp(-580/T ) cm molecule s (IUPAC, current recommendation) and k(HO + CH CH F) = 6.12 × 10 T 3 2 3 −1 −1 exp(-275/T ) cm molecule s (IUPAC, current recommendation). (d) Relative to HO + CH CHF . 3 2 (e) Relative to HO + CH CH F. 3 2 Preferred Values −13 3 −1 −1 k = 1.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.8× 10 exp(-860/T ) cm molecule s over the temperature range 210-400 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4299 Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 150 K. Comments on Preferred Values The absolute room temperature rate coefﬁcients of Howard and Evenson (1976), Perry et al. (1976), Jeong and Kaufman (1982) and Taylor et al. (1993) are signiﬁcantly higher than those of Davis et al. (1976), Villenave et al. (1997) and Herndon et al. (2001), possibly because of the presence of reactive impurities (including stabilizers) present in the CH Cl samples used 2 2 (Villenave et al., 1997; Herndon et al., 2001). The relative rate data of Cox et al. (1976) and Hsu and DeMore (1994) are in reasonable agreement with the absolute rate coefﬁcients of Villenave et al. (1997) and Herndon et al. (2001). An Arrhenius plot of the absolute rate data of Villenave et al. (1997) and Herndon et al. (2001) shows little or no evidence for curvature over the temperature range studied (219–394 K). Accordingly, the preferred Arrhenius expression is obtained from a unit- weighted least-squares analysis of the absolute rate coefﬁcients of Villenave et al. (1997) and Herndon et al. (2001). The room temperature relative rate constant of Cox et al. (1976) agrees well with the preferred 298 K value, while the rate coefﬁcients of Hsu and DeMore (1994) relative to HO + CH CHF are ∼5-10% lower than the preferred values and those relative to HO + 3 2 CH CH F are∼15-20% higher than the preferred values over the temperature ranges 298–360 K and 298–368 K, respectively. 3 2 References Cox, R. A., Derwent, R. G., Eggleton, A. E. J. and Lovelock, J. E.: Atmos. Environ., 10, 305, 1976. Davis, D. D., Machado, G., Conaway, B., Oh, Y. and Watson, R. T.: J. Chem. Phys., 65, 1268, 1976. Herndon, S. C., Gierczak, T., Talukdar, R. K. and Ravisahankara, A. R.: Phys. Chem. Chem. Phys., 3, 4529, 2001. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. Hsu, K.-J. and DeMore, W. B.: Geophys. Res. Lett., 21, 805, 1994. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem., 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem., 88, 1222, 1984. Perry, R. A., Atkinson, R. and Pitts, J. N. Jr.: J. Chem. Phys., 64, 1618, 1976. Taylor, P. H., Jiang, Z. and Dellinger, B.: Int. J. Chem. Kinet., 25, 9, 1993. Taylor, P. H., D’Angelo, J. A., Martin, M. C., Kasner, J. H. and Dellinger, B.: Int. J. Chem. Kinet., 21, 829, 1989. Villenave, E., Orkin, V. L., Huie, R. E. and Kurylo, M. J. J.: Phys. Chem. A, 101, 8513, 1997. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4300 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.114 HO + CHF Cl→ H O + CF Cl 2 2 2 ◦ −1 1H = -74.4 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 1.21× 10 exp[-(1636± 151)/T ] 297-434 Atkinson et al., 1976 FP-RF −15 (4.75± 0.48)× 10 296.9 −15 (3.4± 0.7)× 10 296± 2 Howard and Evenson, 1976 DF-LMR −13 9.25× 10 exp[-(1575± 71)/T ] 250-350 Watson et al., 1977 FP-RF −15 (4.8± 0.46)× 10 298 −12 1.20× 10 exp[-(1657± 39)/T ] 253-427 Chang and Kaufman, 1977 DF-RF −15 (4.25± 0.28)× 10 296 −12 2.1× 10 exp[-(1780± 150)/T ] 263-373 Handwerk and Zellner, 1978 FP-RA −15 (4.6± 0.8)× 10 293 −12 9.5× 10 exp[-(2300± 200)/T ] 294-426 Clyne and Holt, 1979 DF-RF −15 (3.3± 0.7)× 10 294 −15 (4.58± 0.59)× 10 297 Paraskevopoulos et al., 1981 FP-RA −28 5.11 5.03× 10 T exp[-(252± 780)/T ] 293-492 Jeong and Kaufman, 1982; DF-RF −15 (4.83± 0.32)× 10 293 Jeong et al., 1984 −13 8.1× 10 exp[-(1516± 53)/T ] 298-460 Orkin and Khamaganov, 1993 DF-EPR −15 (4.9± 0.45)× 10 298 −12 1.74× 10 exp[-(1701± 39)/T ] 302-382 Yujing et al., 1993 DF-RF −15 5.99× 10 302 Absolute Rate Coefﬁcients −22 3.28 1.31× 10 T exp[-(361± 564)/T ] 294-807 Fang et al., 1996 PLP-LIF −15 (4.65± 0.66)× 10 294 Relative Rate Coefﬁcients −21 2.82 4.44× 10 T exp[-(645± 45)/T ] 298-366 Hsu and DeMore, 1995 RR (a) −15 4.83× 10 298 Comments (a) HO radicals were generated by the UV photolysis of O in the presence of water vapor. The concentrations of CHF Cl 3 2 and CH were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHF Cl)/k(HO + CH ) 4 2 4 = (0.24 ± 0.03) exp[(342 ± 45)/T ] is placed on an absolute basis by using a rate coefﬁcient of k(HO + CH ) = 1.85 × −20 2.82 3 −1 −1 10 T exp(-987/T ) cm molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 4.7× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 7.9× 10 exp(-1530/T ) cm molecule s over the temperature range 240-300 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4301 Reliability 1 log k =± 0.08 at 298 K. 1 (E/R) =± 150 K. Comments on Preferred Values The absolute rate coefﬁcients of Atkinson et al. (1975), Howard and Evenson (1976), Watson et al. (1977), Chang and Kaufman (1977), Handwerk and Zellner (1978), Paraskevopoulos et al. (1981), Jeong and Kaufman (1982), Orkin and Khamaganov (1993) and Fang et al. (1996) are in good agreement, and the relative rate coefﬁcients of Hsu and DeMore (1995) agree well with these absolute rate coefﬁcients. The absolute rate coefﬁcients of Clyne and Holt (1979) exhibit a signiﬁcantly higher temperature dependence than those determined in the other absolute rate studies, and the rate coefﬁcients of Yujing et al. (1993) are signiﬁcantly higher those of Atkinson et al. (1975), Howard and Evenson (1976), Watson et al. (1977), Chang and Kaufman (1977), Handwerk and Zellner (1978), Paraskevopoulos et al. (1981), Jeong and Kaufman (1982), Orkin and Khamaganov (1993) and Fang et al. (1996). Accordingly, the studies of Clyne and Holt (1979) and Yujing et al. (1993) are not used in the evaluation of the rate coefﬁcient for this reaction. The absolute rate coefﬁcients of Atkinson et al. (1975), Howard and Evenson (1976), Watson et al. (1977), Chang and Kaufman (1977), Handwerk and Zellner (1978), Paraskevopoulos et al. (1981), Jeong and Kaufman (1982), Orkin and Khamaganov (1993) and Fang et al. (1996) have been ﬁtted to the 2 −18 2 3 −1 −1 three parameter equation k = CT exp(-D/T ), resulting in k = 1.52 × 10 T exp(-1000/T ) cm molecule s over the temperature range 250–807 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, 2 2 T , of 265 K and is obtained from the three parameter equation with A = Ce T and B = D+ 2T . The relative rate data of m m Hsu and DeMore (1995) agree to within 3% with the preferred values. References Atkinson, R., Hansen, D. A. and Pitts, J. N. Jr.: J. Chem. Phys., 63, 1703, 1975. Chang, J. S. and Kaufman, F.: J. Chem. Phys., 66, 4989, 1977. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Fang, T. D., Taylor, P. H. and Dellinger, B.: J. Phys. Chem., 100, 4048, 1996. Handwerk, V. and Zellner, R.: Ber. Bunsenges. Phys. Chem., 82, 1161, 1978. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem., 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem., 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem., 88, 1222, 1984. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem., 16, 157, 1993. Paraskevopoulos, G., Singleton, D. L. and Irwin, R. S.: J. Phys. Chem., 85, 561, 1981. Watson, R. T., Machado, G., Conaway, B., Wagner, S. and Davis, D. D.: J. Phys. Chem., 81, 256, 1977. Yujing, M., Wenxiang, Y., Yuexiang, P. and Lianxiong, Q.: J. Environ. Sci., 5, 481, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4302 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.115 HO + CHFCl → H O + CFCl 2 2 2 ◦ −1 1H = -83.2 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (2.6± 0.4)× 10 296± 2 Howard and Evenson, 1976 DF-LMR −12 1.75× 10 exp[-(1253± 151)/T ] 298-422 Perry et al., 1976 FP-RF −14 (2.7± 0.3)× 10 298.4 −12 1.87× 10 exp[-(1245± 26)/T ] 245-375 Watson et al., 1977 FP-RF −14 (2.88± 0.24)× 10 298 −12 1.16× 10 exp[-(1073± 40)/T ] 241-396 Chang and Kaufman, 1977 DF-RF −14 (3.04± 0.11)× 10 296 −12 4.8× 10 exp[-(1400± 100)/T ] 293-413 Clyne and Holt, 1979 DF-RF −14 (3.54± 0.26)× 10 293 −14 (3.39± 0.87)× 10 297 Paraskevopoulos et al., 1981 FP-RA −18 1.94 1.97× 10 T exp[-(382± 413)/T ] 250-483 Jeong and Kaufman, 1982 DF-RF −14 (3.37± 0.22)× 10 295 Jeong et al., 1984 −15 1.11 1.53× 10 T exp[-(1078± 262)/T ] 295-810 Fang et al., 1996 PLP-LIF −14 (2.48± 0.67)× 10 295 Preferred Values −14 3 −1 −1 k = 2.9× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.04× 10 exp(-1065/T ) cm molecule s over the temperature range 240-300 K. Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The absolute rate coefﬁcients of Clyne and Holt (1979) are signiﬁcantly higher than those of Howard and Evenson (1976), Perry et al. (1976), Watson et al. (1977), Chang and Kaufman (1977), Paraskevopoulos et al. (1981), Jeong and Kaufman (1982) and Fang et al. (1996), and are therefore not used in the evaluation. The absolute rate coefﬁcients of Howard and Evenson (1976), Perry et al. (1976), Watson et al. (1977), Chang and Kaufman (1977), Paraskevopoulos et al. (1981), Jeong and Kaufman (1982) and Fang et al. (1996) have been ﬁtted to the three parameter equation k = CT exp(-D/T ), resulting −18 2 3 −1 −1 in k = 2.00 × 10 T exp(-535/T ) cm molecule s over the temperature range 241–810 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 265 K and is obtained from the three parameter 2 2 equation with A = Ce T and B = D+ 2T . References Chang, J. S. and Kaufman, F.: J. Chem. Phys., 66, 4989, 1977. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Fang, T. D., Taylor, P. H. and Dellinger, B.: J. Phys. Chem., 100, 4048, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4303 Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem., 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem., 88, 1222, 1984. Paraskevopoulos, G., Singleton, D. L. and Irwin, R. S.: J. Phys. Chem., 85, 561, 1981. Perry, R. A., Atkinson, R. and Pitts, J. N. Jr.: J. Chem. Phys., 64, 1618, 1976. Watson, R. T., Machado, G., Conaway, B., Wagner, S. and Davis, D. D.: J. Phys. Chem., 81, 256, 1977. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4304 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.116 HO + CHCl → H O + CCl 3 2 3 ◦ −1 1H = -104.6 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (1.01± 0.15)× 10 296± 2 Howard and Evenson, 1976 DF-LMR −12 4.69× 10 exp[-(1134± 108)/T ] 245-375 Davis et al., 1976 FP-RF −13 (1.14± 0.07)× 10 298 −20 2.65 6.91× 10 T exp[-(262± 398)/T ] 249-487 Jeong and Kaufman, 1982; DF-RF −13 (1.01± 0.065)× 10 298 Jeong et al., 1984 −17 1.52 4.65× 10 T exp[-(261± 42)/T ] 295-775 Taylor et al., 1993 PLP-LIF (a) −13 (1.12± 0.10)× 10 295 Relative Rate Coefﬁcients −13 1.53× 10 298 Cox et al., 1976 RR (b) −18 2 1.46× 10 T exp[-(85± 64)/T ] 288-357 Hsu and DeMore, 1994 RR (c) −14 9.75× 10 298 Comments (a) These data supersede the earlier data from this group (Taylor et al., 1989). (b) HO radicals were generated by the photolysis of HONO-air mixtures at 1.013 bar pressure. Relative rate coefﬁcients were obtained from measurements of the rates of NO formation as a function of the HONO and organic concentrations. Based −15 on the effect of CHCl on NO formation and a rate coefﬁcient for the reaction of HO radicals with CH of 6.4 × 10 3 4 3 −1 −1 cm molecule s at 298 K (IUPAC, current recommendation), the rate coefﬁcient cited in the table is obtained. (c) HO radicals were generated by the UV photolysis of O in the presence of water vapor. The concentrations of CHCl 3 3 and CH CHF were measured by FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHCl )/k(HO + 3 2 3 CH CHF ) = (0.52 ± 0.11) exp[(495 ± 64)/T ] is placed on an absolute base by using a rate coefﬁcient of k(HO + 3 2 −18 2 3 −1 −1 CH CHF ) = 2.80× 10 T exp(-580/T ) cm molecule s (IUPAC, current recommendation). 3 2 Preferred Values −13 3 −1 −1 k = 1.05× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.8× 10 exp(-850/T ) cm molecule s over the temperature range 240–300 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The measured rate data for this reaction exhibit a large amount of scatter, with the room temperature rate coefﬁcients of Howard and Evenson (1976), Davis et al. (1976), Jeong and Kaufman (1982), Taylor et al. (1993) and Hsu and DeMore Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4305 −14 3 −1 −1 −13 3 −1 −1 (1994) ranging from 9.75× 10 cm molecule s to 1.14× 10 cm molecule s . Furthermore, the temperature dependencies obtained by Davis et al. (1976), Jeong and Kaufman (1982), Taylor et al. (1993) and Hsu and DeMore (1994) differ signiﬁcantly, with Davis et al. (1976) and Jeong and Kaufman (1982) determining larger temperature dependencies than obtained by Taylor et al. (1992) and Hsu and DeMore (1994). Note that only two rate coefﬁcients have been measured at temperatures <288 K, one by Davis et al. (1976) at 245 K and the other by Jeong and Kaufman (1982) at 249 K. The 298 K preferred value is an average of the room temperature rate coefﬁcients of Howard and Evenson (1976), Davis et al. (1976), Jeong and Kaufman (1982), Taylor et al. (1993) and Hsu and DeMore (1994). The temperature dependence for the temperature range 240–300 K is obtained by averaging the Arrhenius activation energies centered on a mid-range temperature, T , of 265 K, with those of Jeong and Kaufman (1982), Taylor et al. (1993) and Hsu and DeMore (1994) being derived from the three parameter expressions cited in the table with B = D + 2T (the Arrhenius activation energies being 1134 K for the Davis et al. (1976) study, 964 K for the Jeong and Kaufman (1982) study, 664 K for the Taylor et al. (1993) study and 615 K for the Hsu and DeMore (1994) study, all centered at 265 K). The preferred Arrhenius expression, which should not be used outside of the temperature range 240–300 K, leads to rate coefﬁcients at 245 K and 249 K which are 28% and 8% higher than those measured by Davis et al. (1976) and Jeong and Kaufman et al. (1982), respectively (note that the recommended −18 2 Arrhenius expression for the temperature range 240–300 K is equivalent to the three parameter equation k = 3.47× 10 T 3 −1 −1 exp(-320/T ) cm molecule s ). Clearly, additional studies of this reaction covering the temperature range∼200–400 K are needed. References Cox, R. A., Derwent, R. G., Eggleton, A. E. J. and Lovelock, J. E.: Atmos. Environ., 10, 305, 1976. Davis, D. D., Machado, G., Conaway, B., Oh, Y. and Watson, R. T.: J. Chem. Phys., 65, 1268, 1976. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. Hsu, K.-J. and DeMore, W. B.: Geophys. Res. Lett., 21, 805, 1994. IUPAC: http://www,iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: J. Phys. Chem., 86, 1808, 1982. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem., 88, 1222, 1984. Taylor, P. H., Jiang, Z. and Dellinger, B.: Int. J. Chem. Kinet., 25, 9, 1993. Taylor, P. H., D’Angelo, J. A., Martin, M. C., Kasner, J. H. and Dellinger, B.: Int. J. Chem. Kinet., 21, 829, 1989. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4306 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.117 HO + CF Cl → HOCl + CF Cl 2 2 2 ◦ −1 1H = 99.0 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 <1× 10 296-424 Atkinson et al., 1975 FP-RF −16 <4× 10 296± 2 Howard and Evenson, 1976 DF-LMR −16 <6× 10 478 Chang and Kaufman, 1977 DF-RF −15 <1× 10 293 Clyne and Holt, 1979 DF-RF Relative Rate Coefﬁcients −17 <9× 10 298 Cox et al., 1976 RR (a) Comments (a) HO radicals were generated by the photolysis of HONO-air mixtures at 1.013 bar pressure. Relative rate coefﬁcients were obtained from measurements of the rates of NO formation as a function of the HONO and organic concentrations. Based on the lack of effect of CF Cl on NO formation and a rate coefﬁcient for the reaction of HO radicals with CH of 6.4× 2 2 4 −15 3 −1 −1 10 cm molecule s at 298 K (IUPAC, current recommendation), the upper limit to the rate coefﬁcient cited in the table is obtained. Preferred Values −18 3 −1 −1 k <7× 10 cm molecule s at 298 K. −12 3 −1 −1 k <1× 10 exp(-3540/T ) cm molecule s over the temperature range 250-480 K. Comments on Preferred Values The studies of Atkinson et al. (1975), Cox et al. (1976), Howard and Evenson (1976), Chang and Kaufman (1977) and Clyne and Holt (1979) all observed no reaction of HO radicals with CF Cl . The preferred upper limit Arrhenius expression 2 2 −12 3 −1 −1 is obtained from an assumed Arrhenius pre-exponential factor of 1 × 10 cm molecule s and the upper limit rate coefﬁcient at 478 K measured by Chang and Kaufman (1977). The resulting upper limit Arrhenius expression yields a 298 K upper limit rate coefﬁcient which is consistent with the room temperature data of Atkinson et al. (1975), Cox et al. (1976), Howard and Evenson (1976) and Clyne and Holt (1979). References Atkinson, R., Hansen, D. A. and Pitts, J. N. Jr.: J. Chem. Phys., 63, 1703, 1975. Chang, J. S. and Kaufman, F.: Geophys. Res. Lett., 4, 192, 1977. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 569, 1979. Cox, R. A., Derwent, R. G., Eggleton, A. E. J. and Lovelock, J. E.: Atmos. Environ., 10, 305, 1976. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4307 IV.A2.118 HO + CFCl → HOCl + CFCl 3 2 ◦ −1 1H = 80.6 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 <1× 10 296-424 Atkinson et al., 1975 FP-RF −16 <5× 10 296± 2 Howard and Evenson, 1976 DF-LMR −16 <5× 10 480 Chang and Kaufman, 1977 DF-RF −15 <1× 10 293 Clyne and Holt, 1979 DF-RF Relative Rate Coefﬁcients −17 <4× 10 298 Cox et al., 1976 RR (a) Comments (a) HO radicals were generated by the photolysis of HONO-air mixtures at 1013 mbar pressure. Relative rate coefﬁcients were obtained from measurements of the rates of NO formation as a function of the HONO and organic concentrations. Based on the lack of effect of CFCl on NO formation and a rate coefﬁcient for the reaction of HO radicals with CH of 3 4 −15 3 −1 −1 6.4× 10 cm molecule s at 298 K (IUPAC, current recommendation), the upper limit to the rate coefﬁcient cited in the table is obtained. Preferred Values −18 3 −1 −1 k <5× 10 cm molecule s at 298 K. −12 3 −1 −1 k <1× 10 exp(-3650/T ) cm molecule s over the temperature range 250-480 K. Comments on Preferred Values The studies of Atkinson et al. (1975), Cox et al. (1976), Howard and Evenson (1976), Chang and Kaufman (1977) and Clyne and Holt (1979) all observed no reaction of HO radicals with CFCl . The preferred upper limit Arrhenius expression is obtained −12 3 −1 −1 from an assumed Arrhenius pre-exponential factor of 1 × 10 cm molecule s and the upper limit at 480 K measured by Chang and Kaufman (1977). The resulting upper limit Arrhenius expression yields a 298 K upper limit rate coefﬁcient which is consistent with the room temperature data of Atkinson et al. (1975), Cox et al. (1976), Howard and Evenson (1976) and Clyne and Holt (1979). References Atkinson, R., Hansen, D. A. and Pitts, J. N., Jr.: J. Chem. Phys., 63, 1703, 1975. Chang, J. S. and Kaufman, F.: Geophys. Res. Lett., 4, 192, 1977. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 569, 1979. Cox, R. A., Derwent, R. G., Eggleton, A. E. J. and Lovelock, J. E.: Atmos. Environ., 10, 305, 1976. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4308 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.119 HO + CCl → HOCl + CCl 4 3 ◦ −1 1H = 51.7 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 <4× 10 296± 2 Howard and Evenson, 1976 DF-LMR −15 <1× 10 293 Clyne and Holt, 1979 DF-RF Relative Rate Coefﬁcients −17 <9× 10 298 Cox et al., 1976 RR (a) Comments (a) HO radicals were generated by the photolysis of HONO-air mixtures at 1013 mbar pressure. Relative rate coefﬁcients were obtained from measurements of the rates of NO formation as a function of the HONO and organic concentrations. Based on the lack of effect of CCl on NO formation and a rate coefﬁcient for the reaction of HO radicals with CH of 4 4 −15 3 −1 −1 6.4× 10 cm molecule s at 298 K (IUPAC, current recommendation), the upper limit to the rate coefﬁcient cited in the table is obtained. Preferred Values −16 3 −1 −1 k <5× 10 cm molecule s at 298 K. −12 3 −1 −1 k <1× 10 exp(-2260/T ) cm molecule s over the temperature range∼250–300 K. Comments on Preferred Values The studies of Cox et al. (1976), Howard and Evenson (1976) and Clyne and Holt (1979) all observed no reaction of HO radicals with CCl . The preferred upper limit to the 298 K rate coefﬁcient is based on the data of Cox et al. (1976), increased by a factor of 5 to take into account uncertainties in the number of NO molecules reacted per CCl reacted, and the upper limit Arrhenius expression combines the preferred upper limit rate coefﬁcient at 298 K with an assumed Arrhenius pre-exponential −12 3 −1 −1 factor of 1× 10 cm molecule s . References Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 569, 1979. Cox, R. A., Derwent, R. G., Eggleton, A. E. J. and Lovelock, J. E.: Atmos. Environ., 10, 305, 1976. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4309 IV.A2.120 HO + C HCl → products 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (2.0± 0.4)× 10 296 Howard, 1976 DF-LMR −13 5.32× 10 exp[(445± 41)/T ] 234-420 Chang and Kaufman, 1977 DF-RF −12 (2.37± 0.10)× 10 296 −12 2.11× 10 305 Kirchner, 1983 DF-MS −13 7.80× 10 exp[(241± 61)/T ] 300-459 Kirchner et al., 1990 DF-MS −12 (1.76± 0.17)× 10 300 −13 9.73× 10 exp[(158.7± 44.0)/T ] 291-650 Tichenor et al., 2000; 2001 PLP-LIF (a) −12 1.66× 10 298 Relative Rate Coefﬁcients −12 (4.3± 1.3)× 10 305± 2 Winer et al., 1976 RR (b) −12 (2.64± 0.37)× 10 296 Edney et al., 1986 RR (c) −12 2.65× 10 300 Klopf ¨ fer et al., 1986 RR (d) Comments (a) This study was stated to supersede the earlier study of Jiang et al. (1993). Tichenor et al. (2000) ﬁt their data, obtained −21 2.76 over the temperature range 291–750 K, by the three parameter expression k = 3.76× 10 T exp[-(1266.3± 41.2)/T ] 3 −1 −1 cm molecule s . (b) HO radicals were generated by the photolysis of NO -organic-air mixtures at ∼1 bar of air. Trichloroethene and 2-methylpropene (the reference compound) were monitored by GC. The measured rate coefﬁcient ratio k(HO + trichloroethene)/k(HO + 2-methylpropene) = 0.088 (±30%) is placed on an absolute basis by use of a rate coefﬁcient −11 3 −1 −1 of k(HO + 2-methylpropene) = 4.94× 10 cm molecule s at 305 K (Atkinson, 1997). (c) HO radicals were generated by the photolysis of CH ONO-NO-air mixtures at∼1 bar of air. Trichloroethene and n-butane (the reference compound) were monitored by GC. The measured rate coefﬁcient ratio k(HO + trichloroethene)/k(HO + −12 3 −1 n-butane) is placed on an absolute basis by use of a rate coefﬁcient of k(HO + n-butane) = 2.33× 10 cm molecule −1 s at 296 K (Atkinson, 2003). (d) HO radicals were generated by the photolysis of NO -organic-air mixtures at∼1 bar of air. Trichloroethene and toluene (the reference compound) were monitored by GC. The measured rate coefﬁcient ratio k(HO + trichloroethene)/k(HO + −12 3 −1 toluene) is placed on an absolute basis by use of a rate coefﬁcient of k(HO + toluene) = 5.58 × 10 cm molecule −1 s at 300 K (Calvert et al., 2002). Preferred Values −12 3 −1 −1 k = 2.0× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 3.0× 10 exp(565/T ) cm molecule s over the temperature range 230-300 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 200 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4310 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values There is a signiﬁcant degree of scatter in both the measured room temperature rate coefﬁcients and the temperature dependence of the rate coefﬁcient, with the room temperature relative rate coefﬁcient from the Winer et al. (1976) study being much higher than those measured in the other studies (possibly because of the disparity between the reactivities of trichloroethene and the reference compound used). An Arrhenius plot of the rate coefﬁcients of Howard (1976), Chang and Kaufman (1977) and Tichenor et al. (2001) suggests curvature [as also concluded by Tichenor et al. (2000)]. Accordingly, the absolute rate coefﬁcients at≤650 K from the studies of Howard (1976), Chang and Kaufman (1977) and Tichenor et al. (2001) were ﬁtted 2 −19 2 3 −1 −1 to the three parameter expression k = CT exp(-D/T ), resulting in k = 6.06 × 10 T exp(1084/T ) cm molecule s over the temperature range 234–650 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range 2 2 temperature, T , of 260 K and is obtained from the three parameter equation with A = C e T and B = D+ 2T . The room m m temperature rate coefﬁcients measured by Kirchner (1983), Edney et al. (1986), Klopf ¨ fer et al. (1986) and Kirchner et al. (1990), which are not used in the derivation of the preferred values, are in general agreement with the preferred values, and the temperature dependence reported by Kirchner et al. (1990) over the temperature range 300–459 K of B = -241 ± 61 K is in reasonable agreement with the value of B = -364 K derived from the preferred three parameter expression centered on a T of 360 K. The reaction proceeds by initial HO radical addition to form the HOCHClCCl and HOCCl CHCl radicals, which under 2 2 atmospheric conditions lead to the formation of Cl atoms, HC(O)Cl, C(O)Cl and other, as yet unidentiﬁed, products (Tuazon et al., 1988; Kleindienst et al., 1989). References Atkinson, R.: J. Phys. Chem. Ref. Data, 26, 215, 1997. Atkinson, R.: Atmos. Chem. Phys., 3, 2233, 2003. Calvert, J. G., Atkinson, R., Becker, K. H., Kamens, R. M., Seinfeld, J. H., Wallington, T. J. and Yarwood, G.: The Mechanisms of Atmospheric Oxidation of Aromatic Hydrocarbons, Oxford University Press, New York, NY, 2002. Chang, J. S. and Kaufman, F.: J. Chem. Phys., 66, 4989, 1977. Edney, E. O., Kleindienst, T. E. and Corse, E. W.: Int. J. Chem. Kinet., 18, 1355, 1986. Howard, C. J.: J. Chem. Phys., 65, 4771, 1976. Jiang, Z., Taylor, P. H. and Dellinger, B.: J. Phys. Chem., 97, 5050, 1993. Kirchner, K.: Chimia, 37, 1, 1983. Kirchner, K., Helf, D., Ott, P. and Vogt, S.: Ber. Bunsenges. Phys. Chem., 94, 77, 1990. Kleindienst, T. E., Shepson, P. B., Nero, C. and Bufalini, J. J.: Int. J. Chem. Kinet., 21, 863, 1989. Klopf ¨ fer, W., Frank, R., Kohl, E.-G. and Haag, F.: Chemiker-Zeitung, 110, 57, 1986. Tichenor, L. A. B., Lozada-Ruiz, A. J., Yamada, T., El-Sinawi, A., Taylor, P. H., Peng, J., Hu, X. and Marshall, P.: Proc. Combustion Institute, 28, 1495, 2000. Tichenor, L. B., El-Sinawi, A., Yamada, T., Taylor, P. H., Peng, J., Hu, X. and Marshall, P.: Chemosphere, 42, 571, 2001. Tuazon, E. C., Atkinson, R., Aschmann, S. M., Goodman, M. A. and Winer, A. M.: Int. J. Chem. Kinet., 20, 241, 1988. Winer, A. M., Lloyd, A. C., Darnall, K. R. and Pitts, J. N. Jr.: J. Phys. Chem., 80, 1635, 1976. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4311 IV.A2.121 HO + C Cl → products 2 4 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (1.70± 0.34)× 10 296 Howard, 1976 DF-LMR −12 9.44× 10 exp[-(1199± 55)/T ] 297-420 Chang and Kaufman, 1977 DF-RF −13 (1.69± 0.07)× 10 297 −12 5.53× 10 exp[-(1034± 13)/T ] 301-433 Kirchner, 1983; DF-MS −13 (1.73± 0.17)× 10 301 Kirchner et al., 1990 −22 3.2 1.93× 10 T exp[(660.8± 54.6)/T ] 296.5-714 Tichenor et al., 2000 PLP-LIF (a) −13 (1.45± 0.16)× 10 296.5 −12 1.53× 10 exp[-(688.2± 67.5)/T ] 293-720 Tichenor et al., 2001 PLP-LIF −13 (1.52± 0.17)× 10 293 Relative Rate Coefﬁcients −12 (2.2± 0.7)× 10 305± 2 Winer et al., 1976 RR (b) Comments −12 (a) Tichenor et al. (2000) also ﬁt their data to an Arrhenius expression, obtaining k = 1.68× 10 exp[-(764.2± 79.1)/T ] 3 −1 −1 cm molecule s over the same temperature range of 296.5–714 K. (b) HO radicals were generated by the photolysis of NO -organic-air mixtures at ∼1 bar of air. Tetrachloroethene and 2-methylpropene (the reference compound) were monitored by GC. The measured rate coefﬁcient ratio k(HO + tetrachloroethene)/k(HO + 2-methylpropene) = 0.044 (±30%) is placed on an absolute basis by use of a rate coefﬁcient −11 3 −1 −1 of k(HO + 2-methylpropene) = 4.94× 10 cm molecule s at 305 K (Atkinson, 1997). Preferred Values −13 3 −1 −1 k = 1.6× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 3.5× 10 exp(-920/T ) cm molecule s over the temperature range 290-420 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The room temperature absolute rate coefﬁcients of Howard (1976), Chang and Kaufman (1977), Kirchner (1983), Kirchner et al. (1990) and Tichenor et al. (2000; 2001) are in good agreement. The relative rate coefﬁcient of Winer et al. (1976) at 305 K is an order of magnitude higher, presumably in part because of the large difference in reactivities of tetrachloroethene and the 2-methylpropene reference compound. The preferred 298 K value is derived from the mean of the values of Howard (1976), Chang and Kaufman (1977), Kirchner et al. (1990), Tichenor et al. (2000) and Tichenor et al. (2001). The temperature depen- dence of the rate coefﬁcient is the average of the Arrhenius activation energies reported by Chang and Kaufman, Kirchener et al. (1990), Tichenor et al. (2000) and Tichenor et al. (2001), with the pre-exponential factor being adjusted to ﬁt the 298 K preferred value. No rate coefﬁcients are available below 290 K, and additional studies involving measurements down to≤ 220 K are clearly needed. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4312 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry The reaction proceeds by initial HO radical addition to form the HOCCl CCl radical, which under atmospheric conditions 2 2 leads to the formation of Cl atoms, C(O)Cl and other, as yet unidentiﬁed, products (Tuazon et al., 1988). The molar formation yield of C(O)Cl was measured by Tuazon et al. (1988) to be∼0.5 in both the presence and absence of a Cl atom scavenger. References Atkinson, R.: J. Phys. Chem. Ref. Data, 26, 215, 1997. Chang, J. S. and Kaufman, F.: J. Chem. Phys., 66, 4989, 1977. Howard, C. J.: J. Chem. Phys., 65, 4771, 1976. Kirchner, K.: Chimia, 37, 1, 1983. Kirchner, K., Helf, D., Ott, P. and Vogt, S.: Ber. Bunsenges. Phys. Chem., 94, 77, 1990. Tichenor, L. B., Graham, J. L., Yamada, T., Taylor, P. H., Peng, J., Hu, X. and Marshall, P.: J. Phys. Chem. A, 104, 1700, Tichenor, L. B., El-Sinawi, A., Yamada, T., Taylor, P. H., Peng, J., Hu, X. and Marshall, P.: Chemosphere, 42, 571, 2001. Tuazon, E. C., Atkinson, R., Aschmann, S. M., Goodman, M. A. and Winer, A. M.: Int. J. Chem. Kinet., 20, 241, 1988. Winer, A. M., Lloyd, A. C., Darnall, K. R. and Pitts, J. N., Jr.: J. Phys. Chem., 80, 1635, 1976. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4313 IV.A2.122 HO + CH CF Cl→ H O + CH CF Cl 3 2 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 (2.83± 0.42)× 10 296 Howard and Evenson, 1976 DF-LMR −12 1.15× 10 exp[-(1748± 30)/T ] 273-375 Watson et al., 1977 FP-RF −15 (3.22± 0.48)× 10 298 −12 1.8× 10 exp[-(1790± 150)/T ] 293-373 Handwerk and Zellner, 1978 FP-RA −15 (3.7± 0.7)× 10 293 −12 3.3× 10 exp[-(1800± 300)/T ] 293-417 Clyne and Holt, 1979 DF-RF −15 (6.7± 1.3)× 10 298 −15 (4.63± 1.73)× 10 297 Paraskevopoulos et al., 1981 FP-RA −13 9.8× 10 exp[-(1660± 200)/T ] 270-400 Liu et al., 1990 FP-RF −15 (4.02± 1.0)× 10 298 −13 2.6× 10 exp[-(1230± 250)/T ] 231-423 Brown et al., 1990 DF-RF −15 (3.7± 1.4)× 10 303 −12 1.14× 10 exp[-(1750± 75)/T ] 223-374 Gierczak et al., 1991 DF-LMR/FP-LIF (a) −15 (2.95± 0.25)× 10 298 −15 (2.45± 0.31)× 10 270 Zhang et al., 1992 FP-RF −15 (2.6± 0.4)× 10 293 Mors ¨ et al., 1996 PLP-A −30 6.01 2.05× 10 T exp[(308± 522)/T ] 295-808 Fang et al., 1997 PLP-LIF −15 (3.77± 0.43)× 10 295 Relative Rate Coefﬁcients −15 3.5× 10 298 Cox et al., 1976 RR (b) Comments (a) Experiments were carried out over the temperature range 223–427 K. (b) HO radicals were generated by the photolysis of HONO-air mixtures at 1.013 bar pressure. Relative rate coefﬁcients were obtained from measurements of the rates of NO formation as a function of the HONO and organic concentrations. Based on the effect of CH CF Cl on NO formation and a rate coefﬁcient for the reaction of HO radicals with CH of 6.4 × 3 2 4 −15 3 −1 −1 10 cm molecule s at 298 K (IUPAC, current recommendation), the rate coefﬁcient cited in the table is obtained. Preferred Values −15 3 −1 −1 k = 3.0× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 8.5× 10 exp(-1685/T ) cm molecule s over the temperature range 220-300 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 200 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4314 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The rate coefﬁcients obtained exhibit a large degree of scatter, especially at temperatures ≤305 K. In particular, the rate coefﬁcients of Clyne and Holt (1979) and Brown et al. (1990) and, to a lesser extent, those of Handwerk and Zellner (1978), Paraskevopoulos et al. (1981), Liu et al. (1990), Zhang et al. (1992) and Fang et al. (1997) at room temperature and below are higher than those of Howard and Evenson (1976), Watson et al. (1977), Gierczak et al. (1991) and Mors ¨ et al. (1996). Accordingly, the absolute rate coefﬁcients of Howard and Evenson (1976), Watson et al. (1977), Gierczak et al. (1991) and 2 −18 2 Mors ¨ et al. (1996) have been ﬁtted to the three parameter equation k = CT exp(-D/T ), resulting in k = 1.77 × 10 T 3 −1 −1 exp(-1174/T ) cm molecule s over the temperature range 223–427 K. The preferred Arrhenius expression, k = A exp(- B/T ), is centered on a mid-range temperature, T , of 255 K and is obtained from the three parameter equation with A = C e T and B = D+ 2T . References Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ., 24A, 2499, 1990. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Cox, R. A., Derwent, R. G., Eggleton, A. E. J. and Lovelock, J. E.: Atmos. Environ., 10, 305, 1976. Fang, T. D., Taylor, P. H., Dellinger, B., Ehlers, C. J. and Berry, R. J.: J. Phys. Chem. A, 101, 5758, 1997. Gierczak, T., Talukdar, R., Vaghjiani, G. L., Lovejoy, E. R. and Ravishankara, A. R.: J. Geophys. Res., 96, 5001, 1991. Handwerk, V. and Zellner, R.: Ber. Bunsenges. Phys. Chem., 82, 1161, 1978. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 4303, 1976. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Liu, R., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem., 94, 3247, 1990. Mors, ¨ V., Hoffmann, A., Malms, W. and Zellner, R.: Ber. Bunsenges. Phys. Chem., 100, 540, 1996. Paraskevopoulos, G., Singleton, D. L. and Irwin, R. S.: J. Phys. Chem., 85, 561, 1981. Watson, R. T., Machado, G., Conaway, B., Wagner, S. and Davis, D. D.: J. Phys. Chem., 81, 256, 1977. Zhang, Z., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem., 96, 1533, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4315 IV.A2.123 HO + CH CFCl → H O + CH CFCl 3 2 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 3.6× 10 exp[-(1140± 210)/T ] 243-400 Liu et al., 1990 FP-RF −15 (7.01± 1.2)× 10 298 −13 5.8× 10 exp[-(1100± 250)/T ] 238-426 Brown et al., 1990 DF-RF −14 (1.61± 0.55)× 10 297 −12 1.47× 10 exp[-(1640± 100)/T ] 253-393 Talukdar et al., 1991 PLP-LIF/DF-LMR (a) −15 (5.92± 0.54)× 10 298 −15 (1.82± 0.65)× 10 250 Zhang et al., 1992 FP-RF (b) −15 (2.01± 0.90)× 10 250 −15 (3.39± 0.82)× 10 270 −15 (4.80± 1.46)× 10 297 −12 2.4× 10 exp[-(1790± 100)/T ] 298-479 Lancar et al., 1993 DF-EPR −15 (5.7± 1.5)× 10 298 −15 (4.6± 0.8)× 10 293 Mors ¨ et al., 1996 FP-A Relative Rate Coefﬁcients −21 2.82 9.07× 10 T exp[-(798± 105)/T ] 298-358 Huder and DeMore, 1993 RR (c,d) −15 5.91× 10 298 −18 2 1.78× 10 T exp[-(984± 28)/T ] 298-358 Huder and DeMore, 1993 RR (c,e) −15 5.85× 10 298 Comments (a) Experiments were carried out down to 233 K, using highly puriﬁed samples. In the pulsed laser photolysis experiments, photolysis of HONO was used as the HO radical source to avoid photolysis of CH CFCl . An Arrhenius plot of the entire 3 2 dataset showed curvature at the two lowest temperatures studied (233 and 249 K), and the cited Arrhenius expression was derived using only the rate coefﬁcients measured at≥253 K. (b) HO radicals were generated by the pulsed photolysis of H O. Experiments carried out with reduced ﬂash energies or water vapor concentrations (resulting in lower initial HO radical concentrations) led to the lower measured rate coefﬁcients cited in the table. These data supersede those of Liu et al. (1990) at 243–298 K. (c) HO radicals were generated by the photolysis of H O-O mixtures at 254 nm in H O-O -CH CFCl -CH (or CH CCl )- 2 3 2 3 3 2 4 3 3 Ar-O mixtures. The concentrations of CH CFCl and CH (or CH CCl ) were measured by FTIR spectroscopy. The 2 3 2 4 3 3 measured rate coefﬁcient ratios of k(HO + CH CFCl )/k(HO + CH ) = (0.49 ± 0.16) exp[(189 ± 105)/T ] and k(HO + 3 2 4 CH CFCl /k(HO + CH CCl ) = (0.79± 0.07) exp[-(74± 28)/T ] are placed on an absolute basis by use of rate coefﬁcients 3 2 3 3 −20 2.82 3 −1 −1 of k(HO + CH ) = 1.85× 10 T exp(-987/T ) cm molecule s (IUPAC, current recommendation) and k(HO + −18 2 3 −1 −1 CH CCl ) = 2.25× 10 T exp(-910/T ) cm molecule s (IUPAC, current recommendation). 3 3 (d) Relative to k(HO + CH ). (e) Relative to k(HO + CH CCl ). 3 3 Preferred Values −15 3 −1 −1 k = 5.8× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 8.1× 10 exp(-1470/T ) cm molecule s over the temperature range 220-300 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4316 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Reliability 1 log k =± 0.1 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The absolute rate coefﬁcients of Brown et al. (1990) are higher than those from the absolute rate studies of Liu et al. (1990), Talukdar et al. (1991), Zhang et al. (1992), Lancar et al. (1993) and Mors ¨ et al. (1996) at all temperatures studied, and the rate coefﬁcients of Liu et al. (1990) at temperatures≤ 298 K are signiﬁcantly higher than those of Talukdar et al. (1991), Zhang et al. (1992), Lancar et al. (1993) and Mors ¨ et al. (1996). The measurements of Zhang et al. (1992) show that the earlier lower temperature (≤298 K) data of Liu et al. (1990) were in error due to the occurrence of secondary reactions of HO radicals with reaction products. The rate coefﬁcients of Talukdar et al. (1991), Zhang et al. (1992) [obtained at low ﬂash energies and/or low water vapor concentrations and with high associated uncertainties], Lancar et al. (1993), Mors ¨ et al. (1996) and Huder and DeMore (1993) are in good agreement, as are those of Talukdar et al. (1991) and Liu et al. (1990) at temperatures≥ 330 K. The rate coefﬁcients of Talukdar et al. (1991), Zhang et al. (1992), Lancar et al. (1993) and Mors ¨ et al. (1996) have been 2 −18 2 3 −1 ﬁtted to the three parameter equation k = CT exp(-D/T ), resulting in k = 1.68 × 10 T exp(-962/T ) cm molecule −1 s over the temperature range 233–479 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range 2 2 temperature, T , of 255 K and is obtained from the three parameter equation with A = C e T and B = D + 2T . The m m rate coefﬁcients of Huder and DeMore (1993) over the temperature range 298–358 K, obtained relative to the reactions of HO radicals with CH and CH CCl , agree to within 6% with those calculated from the preferred three parameter expression. 4 3 3 References Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ., 24A, 2499, 1990. Huder, K. and DeMore, W. B.: Geophys. Res. Lett., 20, 1575, 1993. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Lancar, I., Le Bras, G. and Poulet, G.: J. Chim. Phys., 90, 1897, 1993. Liu, R., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem., 94, 3247, 1990. Mors, ¨ V., Hoffmann, A., Malms, W. and Zellner, R.: Ber. Bunsenges. Phys. Chem., 100, 540, 1996. Talukdar, R., Mellouki, A., Gierczak, T., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem., 95, 5815, Zhang, Z., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem., 96, 1533, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4317 IV.A2.124 HO + CH CCl → H O + CH CCl 3 3 2 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (1.5± 0.3)× 10 296 Howard and Evenson, 1976 DF-LMR −12 3.72× 10 exp[-(1627± 50)/T ] 260-375 Watson et al., 1977 FP-RF −14 (1.59± 0.16)× 10 298 −12 1.95× 10 exp[-(1331± 37)/T ] 275-406 Chang and Kaufman, 1977 DF-RF −14 (2.19± 0.26)× 10 298 −12 2.4× 10 exp[-(1394± 113)/T ] 293-430 Clyne and Holt, 1979 DF-RF −14 (1.81± 0.16)× 10 293 −12 5.04× 10 exp[-(1797± 65)/T ] 278-457 Jeong and Kaufman, 1979; DF-RF (a) −14 (1.06± 0.11)× 10 293 Jeong et al., 1984 −12 5.4× 10 exp[-(1810± 100)/T ] 253-363 Kurylo et al., 1979 FP-RF −14 (1.08± 0.20)× 10 296 −12 5.4× 10 exp[-(1810± 448)/T ] 359-402 Nelson et al., 1990 PR-RA −14 1.3× 10 298 −13 9.1× 10 exp[-(1337± 150)/T ] 278-378 Finlayson-Pitts et al., 1992 DF-RF −14 (1.0± 0.1)× 10 298 −12 1.75× 10 exp[-(1550± 100)/T ] 233-379 Talukdar et al., 1992 PLP-LIF/FP-LIF −15 (9.5± 0.8)× 10 298 −18 2.08 2.78× 10 T exp[-(1068± 108)/T ] 298-761 Jiang et al., 1992 PLP-LIF −14 (1.1± 0.1)× 10 298 −14 (1.2± 0.2)× 10 298 Lancar et al., 1993 DF-EPR Relative Rate Coefﬁcients −14 2.57× 10 298 Cox et al., 1976 RR (b) −15 (9.0± 0.29)× 10 298± 3 Nelson et al., 1990 RR (c) −20 2.82 1.15× 10 T exp(-696/T ) 277-356 DeMore, 1992 RR (d) −14 (1.06± 0.05)× 10 298 Comments −20 2.65 3 (a) The data were also ﬁtted to a three parameter expression, resulting in k = 5.95 × 10 T exp[-(858 ± 866)/T ] cm −1 −1 molecule s . (b) HO radicals were generated by the photolysis of CH ONO-NO-air mixtures at 1.013 bar pressure. Relative rate coefﬁ- cients were obtained from measurements of the rates of NO formation as a function of the HONO and organic concentra- tions. Based on the effect of CH CCl on NO formation and a rate coefﬁcient for the reaction of HO radicals with CH 3 3 4 −15 3 −1 −1 of 6.4× 10 cm molecule s at 298 K (IUPAC, current recommendation), the rate coefﬁcient cited in the table is obtained. (c) HO radicals were generated by the photolysis of HONO-air mixtures at 987 mbar pressure. CH CCl and CH Cl 3 3 3 (the reference compound) were monitored during the experiments by GC. The measured rate coefﬁcient ratio k(HO + −14 CH CCl )/k(HO + CH Cl) is placed on an absolute basis by use of a rate coefﬁcient of k(HO + CH Cl) = 3.6 × 10 3 3 3 3 3 −1 −1 cm molecule s at 298 K (IUPAC, current recommendation). (d) HO radicals were generated by the photolysis of O at 254 nm in H O-O -CH CCl -CH -Ar-O mixtures. The con- 3 2 3 3 3 4 2 centrations of CH CCl and CH were measured by FTIR spectroscopy. The measured rate coefﬁcient ratios of k(HO + 3 3 4 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4318 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry CH CCl )/k(HO + CH ) = 0.62 exp(291/T ) is placed on an absolute basis by use of a rate coefﬁcient of k(HO + CH ) = 3 3 4 4 −20 2.82 3 −1 −1 1.85× 10 T exp(-987/T ) cm molecule s (IUPAC, current recommendation). Preferred Values −15 3 −1 −1 k = 9.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.2× 10 exp(-1440/T ) cm molecule s over the temperature range 240–300 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The absolute rate coefﬁcients of Finlayson-Pitts et al. (1992) and Talukdar et al. (1992) are lower than the data from the studies of Howard and Evenson (1976), Watson et al. (1977), Chang and Kaufman (1977), Clyne and Holt (1979), Jeong and Kaufman (1979), Kurylo et al. (1979), Nelson et al. (1990), Jiang et al. (1992) and Lancar et al. (1993), in part due to the presence of reactive CH =CCl impurities in the CH CCl samples used (Jeongand Kaufman, 1979; Kurylo et al., 1979) and/or the 2 2 3 3 formation of CH =CCl from thermal decomposition of CH CCl on surfaces (Finlayson-Pitts et al., 1992; Talukdar et al., 2 2 3 3 1992). A unit-weighted least-squares analysis of the absolute rate coefﬁcients of Finlayson-Pitts et al. (1992) and Talukdar et 2 −18 2 3 −1 −1 al. (1992), using the expression k = CT exp(-D/T ), leads to k = 2.25× 10 T exp(-910/T ) cm molecule s over the temperature range 243–379 K. The preferred Arrhenius expression, k = A exp(-B /T), is centered on a mid-range temperature, 2 2 T , of 265 K and is obtained from the three parameter equation with A = C e T and B = D+ 2T . m m The relative rate coefﬁcients of DeMore (1992) are slightly higher than the recommendation over the temperature range studied (277–356 K), by 11–15%. References Chang, J. S. and Kaufman, F.: J. Chem. Phys., 66, 4989, 1977. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 569, 1979. Cox, R. A., Derwent, R. G., Eggleton, A. E. J. and Lovelock, J. E.: Atmos. Environ., 10, 305, 1976. DeMore, W. B.: Geophys. Res. Lett., 19, 1367, 1992. Finlayson-Pitts, B. J., Ezell, M. J., Jayaweera, T. M., Berko, H. N. and Lai, C. C.: Geophys. Res. Lett., 19, 1371, 1992. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 4303, 1976. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Jeong, K.-M. and Kaufman, F.: Geophys. Res. Lett., 6, 757, 1979. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem., 88, 1222, 1984. Jiang, Z., Taylor, P. H. and Dellinger, B.: J. Phys. Chem., 96, 8961, 1992. Kurylo, M. J., Anderson, P. C. and Klais, O.: Geophys. Res. Lett., 6, 760, 1979. Lancar, I., Le Bras, G. and Poulet, G.: J. Chim. Phys., 90, 1897, 1993. Nelson, L., Shanahan, I., Sidebottom, H. W., Treacy, J. and Nielsen, O. J.: Int. J. Chem. Kinet., 22, 577, 1990. Talukdar, R. K., Mellouki, A., Schmoltner, A.-M., Watson, T., Montzka, S. and Ravishankara, A. R.: Science, 257, 227, 1992. Watson, R. T., Machado, G., Conaway, B., Wagner, S. and Davis, D. D.: J. Phys. Chem., 81, 256, 1977. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4319 IV.A2.125 HO + CH ClCF → H O + CHClCF 2 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (1.05± 0.23)× 10 296 Howard and Evenson, 1976 DF-LMR −12 1.1× 10 exp[-(1260± 60)/T ] 263-373 Handwerk and Zellner, 1978 FP-RA −14 (1.5± 0.3)× 10 293 −11 3.3× 10 exp[-(2300± 300)/T ] 294-427 Clyne and Holt, 1979 DF-RF −14 (1.03± 0.30)× 10 294 −18 1.91 3.06× 10 T exp[-(644± 313)/T ] 295-866 Fang et al., 1999 PLP-LIF −14 (1.76± 0.25)× 10 295 Preferred Values −14 3 −1 −1 k = 1.4× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 5.6× 10 exp(-1100/T ) cm molecule s over the temperature range 260-380 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The temperature dependence of the rate coefﬁcients obtained by Clyne and Holt (1979) is signiﬁcantly higher than those measured by Handwerk and Zellner (1978) and Fang et al. (1999), and, as is the case for other haloalkanes, the data of Clyne and Holt (1979) are therefore not used in the evaluation. The rate coefﬁcients of Fang et al. (1999) are consistently higher, by 10-20%, than those of Handwerk and Zellner over the temperature range common to both studies (295–373 K). The preferred temperature dependence is that obtained from a unit-weighted least-squares analysis of the data of Handwerk and Zellner (1978), and the preferred 298 K rate coefﬁcient is the average of those of Howard and Evenson (1976) and Handwerk and Zellner (1978) corrected to 298 K. The pre-exponential factor is adjusted to ﬁt the 298 K preferred rate coefﬁcient. The temperature dependence of the rate data of Fang et al. (1999) corresponds to a value of B in the Arrhenius expression, centered on a mid-range temperature, T , of 300 K, of B = 1217 K, in good agreement with the recommendation. References Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Fang, T. D., Taylor, P. H. and Berry, R. J.: J. Phys. Chem. A, 103, 2700, 1999. Handwerk, V. and Zellner, R.: Ber. Bunsenges. Phys. Chem., 82, 1161, 1978. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 4303, 1976. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4320 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.126 HO + CH ClCF Cl→ H O + CHClCF Cl 2 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 1.87× 10 exp[-(1351± 78)/T ] 250-350 Watson et al., 1979 FP-RF (a) −14 (1.9± 0.2)× 10 298 −26 4.58 5.54× 10 T exp[-(252± 377)/T ] 249-473 Jeong et al., 1984 DF-RF −14 (2.42± 0.16)× 10 297 −19 2.28 8.53× 10 T exp[-(937± 296)/T ] 295-788 Fang et al., 1999 PLP-LIF −14 (1.84± 0.07)× 10 295 Comments (a) The sample of CH ClCF Cl used was shown by GC to contain ∼0.045% of C halogenated alkenes. After correction 2 2 2 for possible contributions to the observed OH radical decays from these measured impurities, assuming a rate coefﬁcient −12 3 −1 −1 for reaction of the C halogenated alkene impurities with HO radicals of 5 × 10 cm molecule s independent −12 3 −1 −1 of temperature, then the rate coefﬁcient was estimated to be 3 × 10 exp(-1578/T ) cm molecule s over the −14 3 −1 −1 temperature range of 250–350 K, with a rate coefﬁcient at 298 K of 1.67× 10 cm molecule s . Preferred Values −14 3 −1 −1 k = 1.7× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 3.5× 10 exp(-1585/T ) cm molecule s over the temperature range 250–350 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The rate coefﬁcients of Jeong et al. (1984) are higher than those of Watson et al. (1979) and Fang et al. (1999), especially at <300 K, suggesting the presence of reactive impurities in the CH ClCF Cl sample used. The rate coefﬁcients of Jeong et 2 2 al. (1984) are therefore not used in the evaluation. The rate coefﬁcients of Fang et al. (1999) at 295 K and 347 K are in good agreement with the corrected data of Watson et al. (1979) at 298 K and 350 K (see Comment (a) above). Accordingly, the absolute rate coefﬁcients of Watson et al. (1979) [corrected for the impurity observed; see Comment (a)] and Fang et al. (1999) 2 −18 2 3 have been ﬁtted to the three parameter equation k = CT exp(-D/T ), resulting in k = 5.72 × 10 T exp(-1006/T ) cm −1 −1 molecule s over the temperature range 250–788 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on 2 2 a mid-range temperature, T , of 290 K and is obtained from the three parameter equation with A = C e T and B = D+ 2T . m m References Fang, T. D., Taylor, P. H. and Berry, R. J.: J. Phys. Chem. A, 103, 2700, 1999. Jeong, K.-M., Hsu, K.-J., Jeffries, J. B. and Kaufman, F.: J. Phys. Chem., 88, 1222, 1984. Watson, R. T., Ravishankara, A. R., Machado, G., Wagner, S. and Davis, D. D.: Int. J. Chem. Kinet., 11, 187, 1979. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4321 IV.A2.127 HO + CHFClCF → H O + CFClCF 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (1.24± 0.19)× 10 296 Howard and Evenson, 1976 DF-LMR −13 6.13× 10 exp[-(1244± 90)/T ] 250-375 Watson et al., 1979 FP-RF −15 (9.4± 0.3)× 10 301 −13 4.45× 10 exp[-(1150± 60)/T ] 210-349 Gierczak et al., 1991 DF-LMR/FP-RF −15 (9.44± 0.75)× 10 298 (a) −20 2.35 7.72× 10 T exp[-(458± 30)/T ] 297-867 Yamada et al., 2000 PLP-LIF −14 (1.08± 0.16)× 10 297 Relative Rate Coefﬁcients −21 2.82 6.48× 10 T exp[-(620± 40)/T ] 298-366 Hsu and DeMore, 1995 RR (b,c) −15 7.68× 10 298 −19 2 8.28× 10 T exp[-(674± 52)/T ] 298-356 Hsu and DeMore, 1995 RR (b,d) −15 7.66× 10 298 Comments (a) Rate coefﬁcients were measured over the temperature range 210–425 K. Those at the highest temperatures (400 K and 425 K) are higher than extrapolation of the linear Arrhenius plot obtained from the 210–349 K data. (b) HO radicals were generated by the photolysis of H O at 185 nm or from O -H O mixtures in the UV, in H O (or H O- 2 3 2 2 2 O )-CHFClCF -CH (or CHF CHF )-O -N mixtures. The concentrations of CHFClCF and CH (or CHF CHF ) were 3 3 4 2 2 2 2 3 4 2 2 measured by FTIR spectroscopy. The measured rate coefﬁcient ratios of k(HO + CHFClCF )/k(HO + CH ) = (0.35 ± 3 4 0.04) exp[(367 ± 40)/T] and k(HO + CHFClCF )/k(HO + CHF CHF ) = (0.46 ± 0.07) exp[(300 ± 52)/T ] are placed 3 2 2 −20 2.82 3 −1 on an absolute basis by using rate coefﬁcients of k(HO + CH ) = 1.85 × 10 T exp(-987/T ) cm molecule −1 −18 2 3 −1 −1 s (IUPAC, current recommendation) and k(HO + CHF CHF ) = 1.80 × 10 T exp(-974/T ) cm molecule s 2 2 (IUPAC, current recommendation). (c) Relative to k(HO + CH ). (d) Relative to k(HO + CHF CHF ). 2 2 Preferred Values −15 3 −1 −1 k = 8.7× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 3.5× 10 exp(-1105/T ) cm molecule s over the temperature range 210–300 K. Reliability 1 log k =± 0.20 at 298 K. 1 (E/R) =± 300 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4322 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values At room temperature, the absolute and relative rate coefﬁcients of Howard and Evenson (1976), Watson et al. (1979), Gierczak et al. (1991), Hsu and DeMore (1995) and Yamada et al. 2000) range over a factor of∼1.6, with the absolute rate coefﬁcient of Howard and Evenson (1976) being the highest, possibly due to the presence of reactive impurities. The absolute rate coefﬁcients of Yamada et al. (2000) are slightly higher than those of Watson et al. (1979) and Gierczak et al. (1991) over the temperature ranges common to these studies (295–375 K and 295–425 K, respectively), with the differences decreasing as the temperature increases [and with the 425 K rate coefﬁcient of Gierczak et al. (1991) being very consistent with the 415 K and 438 K rate coefﬁcients of Yamada et al. (2000)]. The relative rate coefﬁcients of Hsu and DeMore (1995), using both CH and CHF CHF as reference compounds, are consistently lower than the absolute rate coefﬁcients of Watson et al. (1979) and 2 2 Gierczak et al. (1991), by∼15-20% at 298 K. The rate coefﬁcients of Watson et al. (1979), Gierczak et al. (1991) and Hsu and 2 −19 2 DeMore (1995) have been ﬁtted to the three parameter equation k = CT exp(-D/T ), resulting in k = 7.47× 10 T exp(- 3 −1 −1 606/T ) cm molecule s over the temperature range 210–425 K. The preferred Arrhenius expression, k = A exp(-B/T ), is 2 2 centered on a mid-range temperature, T , of 250 K and is derived from the three parameter equation with A = C e T and B = D + 2T . The temperature dependence obtained by Yamada et al. (2000) is in good agreement with the recommendation, corresponding to a value of B in an Arrhenius expression centered at 250 K of B = 1046 K. References Gierczak, T., Talukdar, R., Vaghjiani, G. L., Lovejoy, E. R. and Ravishankara, A. R.: J. Geophys. Res., 96, 5001, 1991. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 4303, 1976. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem., 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Watson, R. T., Ravishankara, A. R., Machado, G., Wagner, S. and Davis, D. D.: Int. J. Chem. Kinet, 11, 187, 1979. Yamada, T., Fang, T. D., Taylor, P. H. and Berry, R. J.: J. Phys. Chem. A, 104, 5013, 2000. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4323 IV.A2.128 HO + CHCl CF → H O + CCl CF 2 3 2 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (2.84± 0.43)× 10 296 Howard and Evenson, 1976 DF-LMR −12 1.24× 10 exp[-(1056± 70)/T ] 245-375 Watson et al., 1979 FP-RF (a) −14 (3.6± 0.4)× 10 298 −12 1.12× 10 exp[-(1000± 100)/T ] 293-429 Clyne and Holt, 1979 DF-RF −14 (3.86± 0.19)× 10 293 −12 1.1× 10 exp[-(1040± 140)/T ] 270-400 Liu et al., 1990 FP-RF −14 (3.52± 0.28)× 10 298 −12 1.18× 10 exp[-(900± 150)/T ] 232-426 Brown et al., 1990 DF-RF −14 (5.9± 0.6)× 10 303 −13 6.5× 10 exp[-(840± 40)/T ] 213-322 Gierczak et al., 1991 DF-LMR/FP-RF (b) −14 (3.69± 0.37)× 10 298 −12 1.1× 10 exp[-(940± 200)/T ] 295-385 Nielsen, 1991 PR-RA −14 (4.3± 1.0)× 10 295 −19 2.88 2.20× 10 T exp[-(226± 51)/T ] 296-866 Yamada et al., 2000 PLP-LIF −14 (3.67± 0.24)× 10 296.3 Relative Rate Coefﬁcients −19 2 7.84× 10 T exp[-(215± 36)/T ] 298-359 Hsu and DeMore, 1995 RR (c) −14 3.38× 10 298 Comments (a) The sample of CHCl CF used was shown by GC to contain 0.0227% of C F HCl and 0.0021% of C F HCl. After 2 3 4 5 2 4 6 correction for possible contributions to the observed OH radical decays from these measured impurities, assuming a −12 3 −1 −1 rate coefﬁcient for reaction of the halogenated alkene impurities with HO radicals of 5 × 10 cm molecule s −12 3 −1 −1 independent of temperature, then the rate coefﬁcient was estimated to be 1.4× 10 exp(-1102/T ) cm molecule s −14 3 −1 −1 over the temperature range of 245–375 K, with a rate coefﬁcient at 298 K of 3.49× 10 cm molecule s . (b) Rate coefﬁcients were measured over the temperature range 213–380 K. (c) HO radicals were generated by the photolysis of H O at 185 nm or O at 254 nm in the presence of H O, in H O (or H O- 2 3 2 2 2 O )-CHCl CF -CH CHF -O -N mixtures. The concentrations of CHCl CF and CH CHF were measured by FTIR 3 2 3 3 2 2 2 2 3 3 2 spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHCl CF )/k(HO + CH CHF ) = (0.28± 0.03) exp[(365± 2 3 3 2 −18 2 36)/T ] is placed on an absolute basis by using a rate coefﬁcient of k(HO + CH CHF ) = 2.80 × 10 T exp(-580/T ) 3 2 3 −1 −1 cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 3.6× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 6.6× 10 exp(-870/T ) cm molecule s over the temperature range 210-300 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 200 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4324 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The absolute rate coefﬁcients of Howard and Evenson (1976), Watson et al. (1979) [corrected for impurities; see Comment (a)], Clyne and Holt (1979), Liu et al. (1990), Gierczak et al. (1991) and Yamada et al. (2000) and the relative rate coefﬁcients of Hsu and DeMore (1995) are in reasonable agreement, but are signiﬁcantly lower than the absolute rate coefﬁcients of Brown et al. (1990) and Nielsen (1991). The absolute rate coefﬁcients of Yamada et al. (2000) tend to be slightly higher than those of Watson et al. (1979) [corrected for impurities], Liu et al. (1990) and Gierczak et al. (1991), while the relative rate coefﬁcients of Hsu and DeMore (1995) tend to be slightly lower. Although in this case the data of Clyne and Holt (1979) are in good agreement with the studies of Howard and Evenson (1976), Watson et al. (1979), Liu et al. (1990), Gierczak et al. (1991) and Yamada et al. (2000), because of discrepancies between their data and those of other investigators for most other haloalkanes studied, the data of Clyne and Holt (1979) have not been used in the evaluation. The rate coefﬁcients of Howard and Evenson (1976), Watson et al. (1979) [corrected for impurities; see Comment (a)], Liu et al. (1990), Gierczak et al. (1991), Yamada et al. (2000) and Hsu and DeMore (1995) have been ﬁtted to the three parameter equation k = CT exp(-D/T ), resulting −18 2 3 −1 −1 in k = 1.42 × 10 T exp(-370/T ) cm molecule s over the temperature range 213–866 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 250 K and is obtained from the three parameter 2 2 equation with A = C e T and B = D+ 2T . References Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ., 24A, 2499, 1990. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 582, 1979. Gierczak, T., Talukdar, R., Vaghjiani, G. L., Lovejoy, E. R. and Ravishankara, A. R.: J. Geophys. Res., 96, 5001, 1991. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 4303, 1976. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem., 99, 1235, 1995. IUPAC: http://www.iupac-kinet.ch.cam.ac.uk/, 2007. Liu, R., Huie, R. E. and Kurylo, M. J.: J. Phys. Chem., 94, 3247, 1990. Nielsen, O. J.: Chem. Phys. Lett., 187, 286, 1991. Watson, R. T., Ravishankara, A. R., Machado, G., Wagner, S. and Davis, D. D.: Int. J. Chem. Kinet., 11, 187, 1979. Yamada, T., Fang, T. D., Taylor, P. H. and Berry, R. J.: J. Phys. Chem. A, 104, 5013, 2000. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4325 IV.A2.129 HO + CHFClCF Cl→ H O + CFClCF Cl 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 9.2× 10 exp[-(1281± 85)/T ] 298-460 Orkin and Khamaganov, 1993 DF-EPR −14 (1.23± 0.10)× 10 298 Preferred Values −14 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 8.4× 10 exp(-1255/T ) cm molecule s over the temperature range 290-460 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The preferred Arrhenius expression is obtained from a unit-weighted least-squares analysis of the absolute rate coefﬁcients of Orkin and Khamaganov (1993), the sole study conducted to date. References Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem., 16, 157, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4326 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.130 HO + CHCl CF Cl→ H O + CCl CF Cl 2 2 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 1.13× 10 exp[-(918± 52)/T ] 298-460 Orkin and Khamaganov, 1993 DF-EPR −14 (5.30± 0.41)× 10 298 Relative Rate Coefﬁcients −13 9.0× 10 exp[-(868± 32)/T ] 303-363 DeMore, 1996 RR (a,b) −14 ∗ 4.87× 10 298 −18 2 1.36× 10 T exp[-(256± 98)/T ] 313-371 DeMore, 1996 RR (a,c) −14 ∗ 5.12× 10 298 Comments (a) HO radicals were generated by the photolysis of H O at 185 nm or O at 254 nm in the presence of H O, in H O (or 2 3 2 2 H O-O )-CHCl CF Cl-CH Cl (or CHCl CF )-O -N mixtures. The concentrations of CHCl CF Cl and CH Cl (or 2 3 2 2 2 2 2 3 2 2 2 2 2 2 CHCl CF ) were measured by FTIR spectroscopy. The measured rate coefﬁcient ratios of k(HO + CHCl CF Cl)/k(HO 2 3 2 2 + CH Cl ) = (0.50 ± 0.05) exp[-(8 ± 32)/T ] and k(HO + CHCl CF Cl)/k(HO + CHCl CF ) = (0.96 ± 0.28) exp[(114 2 2 2 2 2 3 −12 ± 98)/T ] are placed on an absolute basis by using rate coefﬁcients of k(HO + CH Cl ) = 1.8 × 10 exp(-860/T ) 2 2 3 −1 −1 −18 2 3 cm molecule s (IUPAC, current recommendation) and k(HO + CHCl CF ) = 1.42 × 10 T exp(-370/T ) cm 2 3 −1 −1 molecule s (IUPAC, current recommendation). (b) Relative to k(HO + CH Cl ). 2 2 (c) Relative to k(HO + CHCl CF ). 2 3 Preferred Values −14 3 −1 −1 k = 5.1× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 8.1× 10 exp(-825/T ) cm molecule s over the temperature range 270-340 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values Over the temperature range 298–371 K, the absolute rate coefﬁcients of Orkin and Khamaganov (1993) and the relative rate coefﬁcients of DeMore (1996), using both CH Cl and CHCl CF as reference compounds, are in good agreement. Accord- 2 2 2 3 ingly, the three parameter equation k = CT exp(-D/T ) was ﬁtted to the rate coefﬁcients of Orkin and Khamaganov (1993) −18 2 3 −1 −1 and DeMore (1996), resulting in k = 1.23× 10 T exp(-227/T ) cm molecule s over the temperature range 298–460 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, T , of 300 K and is obtained 2 2 from the three parameter equation with A = C e T and B = D+ 2T . References DeMore, W. B.: J. Phys. Chem., 100, 5813, 1996. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem., 16, 157, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4327 IV.A2.131 HO + CHFClCFCl → H O + CFClCFCl 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −19 2 8.68× 10 T exp[-(463± 42)/T ] 294-362 Hsu and DeMore, 1995 RR (a) −14 1.63× 10 298 Comments (a) HO radicals were generated by the photolysis of H O at 185 nm or O at 254 nm in the presence of H O, in H O (or 2 3 2 2 H O-O )-CHFClCFCl -CH CHF -O -N mixtures. The concentrations of CHFClCFCl and CH CHF were measured 2 3 2 3 2 2 2 2 3 2 by FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHFClCFCl /k(HO + CH CHF ) = (0.31± 0.04) 2 3 2 −18 2 exp[(117 ± 42)/T ] is placed on an absolute basis by using a rate coefﬁcient of k(HO + CH CHF ) = 2.80 × 10 T 3 2 3 −1 −1 exp(-580/T ) cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 1.6× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 5.8× 10 exp(-1065/T ) cm molecule s over the temperature range 270-340 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 400 K. Comments on Preferred Values The preferred values are based on the relative rate coefﬁcients of Hsu and DeMore (1995), the sole study conducted to date. The preferred Arrhenius expression k = A exp(-B/T ) is centered on a mid-range temperature, T , of 300 K and is derived 2 2 2 from the cited three parameter expression, k = CT exp(-D/T ), with A = C e T and B = D+ 2T . References Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem., 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4328 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.132 HO + CHCl CF CF → H O + CCl CF CF 2 2 3 2 2 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 2.3× 10 exp[-(550± 750)/T ] 251-393 Brown et al., 1990 DF-RF −14 (3.7± 0.8)× 10 300 −12 1.92× 10 exp[-(1290± 90)/T ] 270-400 Zhang et al., 1991 FP-RF −14 (2.60± 0.29)× 10 298 −13 6.5× 10 exp[-(970± 115)/T ] 295-364 Nelson et al., 1992 DF-LIF −14 (2.41± 0.24)× 10 295 Preferred Values −14 3 −1 −1 k = 2.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.1× 10 exp(-1130/T ) cm molecule s over the temperature range 270-400 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The rate coefﬁcients measured by Zhang et al. (1991) and Nelson et al. (1992) over the temperature range 295–365 K are in good agreement within the experimental uncertainties. The rate coefﬁcients measured by Brown et al. (1990) at 251 K and 300 K are signiﬁcantly higher, and are not used in the evaluation. The preferred 298 K rate coefﬁcient is the average of those calculated from the Arrhenius expressions of Zhang et al. (1991) and Nelson et al. (1992), and the preferred temperature dependence is the mean of those of Zhang et al. (1991) and Nelson et al. (1992) [a least-squares analysis of the rate coefﬁcients −12 3 −1 −1 of Zhang et al. (1991) and Nelson et al. (1992) yields k = 1.56× 10 exp(-1239/T ) cm molecule s , largely weighted by the 270 K and 400 K rate coefﬁcients of Zhang et al. (1991)]. The pre-exponential factor is adjusted to ﬁt the preferred 298 K rate coefﬁcient and the temperature dependence. References Brown, A. C., Canosa-Mas, C. E., Parr, A. D., Rothwell, K. and Wayne, R. P.: Nature, 347, 541, 1990. Nelson, D. D. Jr., Zahniser, M. S. and Kolb, C. E.: J. Phys. Chem., 96, 249, 1992. Zhang, Z., Liu, R., Huie, R. E. and Kurylo, M. J.: Geophys. Res. Lett., 18, 5, 1991. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4329 IV.A2.133 HO + CHFClCF CF Cl→ H O + CFClCF CF Cl 2 2 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 6.75× 10 exp[-(1300± 180)/T ] 298-400 Zhang et al., 1991 FP-RF −15 (8.6± 1.1)× 10 298 −13 3.9× 10 exp[-(1120± 125)/T ] 295-374 Nelson et al., 1992 DF-LIF −15 (9.0± 1.1)× 10 295 Preferred Values −15 3 −1 −1 k = 8.9× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 5.5× 10 exp(-1230/T ) cm molecule s over the temperature range 290-400 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The preferred values are derived from a least-squares analysis of the rate coefﬁcients of Zhang et al. (1991) and Nelson et al. (1992), which are in excellent agreement. References Nelson, D. D. Jr., Zahniser, M. S. and Kolb, C. E.: J. Phys. Chem., 96, 249, 1992. Zhang, Z., Liu, R., Huie, R. E. and Kurylo, M. J.: Geophys. Res. Lett., 18, 5, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4330 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.134 HO + CH CF CFCl → H O + CH CF CFCl 3 2 2 2 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 7.1× 10 exp[-(1690± 230)/T ] 295-367 Nelson et al., 1992 DF-LIF −15 (2.1± 0.2)× 10 295 Preferred Values −15 3 −1 −1 k = 2.4× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 7.0× 10 exp(-1690/T ) cm molecule s over the temperature range 290-370 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The preferred values are based on the sole study of Nelson et al. (1992). References Nelson, D. D. Jr., Zahniser, M. S. and Kolb, C. E.: J. Phys. Chem., 96, 249, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4331 IV.A2.135 HO + HC(O)Cl→ H O + ClCO Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −13 ≤3.2× 10 299.2 Libuda et al., 1990 RR (a) Comments (a) HO radicals were generated by the thermal decomposition of HO NO after addition of NO to HC(O)Cl-n-butane- 2 2 HO NO -O -N mixtures at 800 mbar pressure. The concentrations of HC(O)Cl and n-butane were monitored by FTIR 2 2 2 2 spectroscopy and GC, respectively. No decay of HC(O)Cl was observed, leading to the upper limit to the rate coefﬁcient cited in the table. Preferred Values −13 3 −1 −1 k <5× 10 cm molecule s at 298 K. Comments on Preferred Values The preferred value is based on the upper limit to the rate coefﬁcient reported by Libuda et al. (1990). References Libuda, H. G., Zabel, F., Fink, E. H. and Becker, K. H.: J. Phys. Chem., 94, 5860, 1990. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4332 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.136 HO + CH OCl→ products Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 2.4× 10 exp[-(360± 100)/T ] 250-341 Crowley et al., 1996 PLP-RF (a) −13 (7.06± 0.22)× 10 294 Comments (a) HO radicals were generated from the pulsed laser photolysis of HNO at 248 nm. CH OCl-Ar samples were shown to be 3 3 stable with respect to decomposition over long time periods (up to 3 months). Each CH OCl-Ar sample used was analyzed for Cl impurities by UV absorption before entering the reaction cell. At 294 K, no effect of total pressure of argon diluent (40–400 mbar) on the measured rate coefﬁcient was observed, and the weighted average 294 K rate coefﬁcient is given in the table. Preferred Values −13 3 −1 −1 k = 7.2× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.4× 10 exp(-360/T ) cm molecule s over the temperature range 250-350 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The preferred values are based on the sole study of this reaction by Crowley et al. (1996). The products have not been measured to date, but formation of H O + CH OCl and HOCl + CH O are possible. 2 2 3 References Crowley, J. N., Campuzano-Jost, P. and Moortgat, G. K.: J. Phys. Chem. 100, 3601, (1996). Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4333 IV.A2.137 HO + C(O)Cl → products Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −15 <1× 10 298± 3 Nelson et al., 1990 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO in CH ONO-NO-C(O)Cl -reference compound-air mixtures at 3 3 2 ∼1 bar pressure. The concentrations of C(O)Cl and the reference compound were monitored during the experiments by GC. No reaction of C(O)Cl was observed. However, no details concerning the reference compound used or the amount of reference compound reacted were given. Preferred Values −15 3 −1 −1 k <5× 10 cm molecule s at 298 K. Comments on Preferred Values The preferred upper limit to the 298 K rate coefﬁcient is based on the sole reported study of Nelson et al. (1990), with the preferred upper limit being increased by a factor of 5 over that cited by Nelson et al. (1990). References Nelson, L., Shanahan, I., Sidebottom, H. W., Treacy, J. and Nielsen, O. J.: Int. J. Chem. Kinet., 22, 577, 1990. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4334 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.138 HO + CH ClCHO → H O + CH ClCO (1) 2 2 2 → H O + CHClCHO (2) Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (3.0± 0.6)× 10 298 Balestra-Garcia et al., 1992 PLP-RF Relative Rate Coefﬁcients −12 (3.2± 0.2)× 10 298± 2 Scollard et al., 1993 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO or C H ONO in CH ONO (or C H ONO)-NO-CH ClCHO- 3 2 5 3 2 5 2 CH C(O)CH CH -air mixtures at 987 ± 13 mbar pressure. The concentrations of CH ClCHO and 2-butanone were 3 2 3 2 measured by GC and/or FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CH ClCHO)/k(HO + 2- −12 3 −1 butanone) is placed on an absolute basis by use of a rate coefﬁcient of k(HO + 2-butanone) = 1.2× 10 cm molecule −1 s at 298 K (IUPAC, current recommendation). Preferred Values −12 3 −1 −1 k = 3.1× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.15 at 298 K. Comments on Preferred Values The preferred 298 K rate coefﬁcient is the average of those of Balestra-Garcia et al. (1992) and Scollard et al. (1993), which are in excellent agreement. The reaction is expected to proceed essentially totally by channel (1) at 298 K. References Balestra-Garcia, C., Le Bras, G. and Mac Leod, H.: J. Phys. Chem., 96, 3312, 1992. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Balestra-Garcia, C., Laverdet, G., LeBras, G., MacLeod, H. and Teton, ´ S.: J. Phys. Chem., 97, 4683, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4335 IV.A2.139 HO + CHFClCHO → H O + CHFClCO (1) → H O + CFClCHO (2) Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (2.2± 0.2)× 10 298± 2 Scollard et al., 1993 PLP-RF Relative Rate Coefﬁcients −12 (1.9± 0.3)× 10 298± 2 Scollard et al., 1993 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO or C H ONO in CH ONO (or C H ONO)-CHFClCHO- 3 2 5 3 2 5 toluene-air mixtures at 987 ± 13 mbar pressure. The concentrations of CHFClCHO and toluene were measured by GC and/or FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHFClCHO)/k(HO + toluene) is placed on an −12 3 −1 −1 absolute basis by using a rate coefﬁcient of k(HO + toluene) = 5.63× 10 cm molecule s at 298 K (Calvert et al., 2002). Preferred Values −12 3 −1 −1 k = 2.1× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.15 at 298 K. Comments on Preferred Values The preferred value is an average of the absolute and relative rate coefﬁcients of Scollard et al. (1993), which are in good agreement. The reaction is expected to proceed by channel (1) at room temperature (Scollard et al., 1993). References Calvert, J. G., Atkinson, R., Becker, K. H., Kamens, R. M., Seinfeld, J. H., Wallington, T. J. and Yarwood, G.: The Mechanism of Atmospheric Oxidation of Aromatic Hydrocarbons, Oxford University Press, New York, NY, 2002. Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Balestra-Garcia, C., Laverdet, G., LeBras, G., MacLeod, H. and Teton, ´ S.: J. Phys. Chem., 97, 4683, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4336 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.140 HO + CHCl CHO → H O + CHCl CO (1) 2 2 2 → H O + CCl CHO (2) 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (2.4± 0.5)× 10 298 Balestra-Garcia et al., 1992 PLP-RF Relative Rate Coefﬁcients −12 (2.4± 0.1)× 10 298± 2 Scollard et al., 1993 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO or C H ONO in CH ONO (or C H ONO)-NO-CHCl CHO- 3 2 5 3 2 5 2 CH C(O)CH CH -air mixtures at 987 ± 13 mbar pressure. The concentrations of CHCl CHO and 2-butanone were 3 2 3 2 measured by GC and/or FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CHCl CHO)/k(HO + 2- −12 3 −1 butanone) is placed on an absolute basis by use of a rate coefﬁcient of k(HO + 2-butanone) = 1.2× 10 cm molecule −1 s at 298 K (IUPAC, current recommendation). Preferred Values −12 3 −1 −1 k = 2.4× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.15 at 298 K. Comments on Preferred Values The preferred 298 K rate coefﬁcient is the average of those of Balestra-Garcia et al. (1992) and Scollard et al. (1993), which are in excellent agreement. The reaction is expected to proceed essentially totally by channel (1) at 298 K (Scollard et al., 1993). References Balestra-Garcia, C., Le Bras, G. and Mac Leod, H. : J. Phys. Chem., 96, 3312, 1992. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Balestra-Garcia, C., Laverdet, G., LeBras, G., MacLeod, H. and Teton, ´ S.: J. Phys. Chem., 97, 4683, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4337 IV.A2.141 HO + CF ClCHO→ H O + CF ClCO 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (9.5± 0.5)× 10 298± 2 Scollard et al., 1993 PLP-RF Relative Rate Coefﬁcients −13 (6.9± 0.5)× 10 298± 2 Scollard et al., 1993 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO or C H ONO in CH ONO (or C H ONO)-CF ClCHO- 3 2 5 3 2 5 2 ethanol-air mixtures at 987 ± 13 mbar pressure. The concentrations of CF ClCHO and ethanol were measured by GC and/or FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CF ClCHO)/k(HO + ethanol) is placed on an −12 3 −1 −1 absolute basis by using a rate coefﬁcient of k(HO + ethanol) = 3.2× 10 cm molecule s at 298 K (IUPAC, current recommendation). Preferred Values −13 3 −1 −1 k = 8.2× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.25 at 298 K. Comments on Preferred Values The preferred value is an average of the absolute and relative rate coefﬁcients of Scollard et al. (1993), which are in reasonable agreement. References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Balestra-Garcia, C., Laverdet, G., LeBras, G., MacLeod, H. and Teton, ´ S.: J. Phys. Chem., 97, 4683, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4338 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.142 HO + CFCl CHO→ H O + CFCl CO 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (1.3± 0.1)× 10 298± 2 Scollard et al., 1993 PLP-RF Relative Rate Coefﬁcients −12 (1.0± 0.2)× 10 298± 2 Scollard et al., 1993 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO or C H ONO in CH ONO (or C H ONO)-CFCl CHO- 3 2 5 3 2 5 2 toluene-air mixtures at 987 ± 13 mbar pressure. The concentrations of CFCl CHO and toluene were measured by GC and/or FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CFCl CHO)/k(HO + toluene) is placed on an −12 3 −1 −1 absolute basis by using a rate coefﬁcient of k(HO + toluene) = 5.63× 10 cm molecule s at 298 K (Calvert et al., 2002). Preferred Values −12 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.15 at 298 K. Comments on Preferred Values The preferred value is an average of the absolute and relative rate coefﬁcients of Scollard et al. (1993), which are in good agreement. References Calvert, J. G., Atkinson, R., Becker, K. H., Kamens, R. M., Seinfeld, J. H., Wallington, T. J. and Yarwood, G.: The Mechanism of Atmospheric Oxidation of Aromatic Hydrocarbons, Oxford University Press, New York, NY, 2002. Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Balestra-Garcia, C., Laverdet, G., LeBras, G., MacLeod, H. and Teton, ´ S.: J. Phys. Chem., 97, 4683, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4339 IV.A2.143 HO + CCl CHO→ H O + CCl CO 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 1.25× 10 exp[-(600± 90)/T ] 298-520 Dob ´ e ´ et al., 1989 DF-RF/LIF −12 (1.56± 0.34)× 10 298 −13 (8.7± 1.7)× 10 298 Balestra-Garcia et al., 1992 PLP-RF −12 (1.28± 0.25)× 10 298± 2 Barry et al., 1994 DF-RF −13 (8.9± 1.5)× 10 298± 2 Barry et al., 1994 DF-EPR −12 1.79× 10 exp[-(240± 60)/T ] 233-415 Talukdar et al., 2001 PLP-LIF −13 (8.3± 0.8)× 10 298 Relative Rate Coefﬁcients −12 (1.63± 0.29)× 10 298± 3 Nelson et al., 1990 RR (a) −12 (1.5± 0.2)× 10 298± 2 Scollard et al., 1993 RR (b) −13 (9.5± 0.3)× 10 298± 2 Barry et al., 1994 RR (c) Comments (a) HO radicals were generated by the photolysis of CH ONO in CH ONO-CCl CHO-ethyl acetate (the reference 3 3 3 compound)-air mixtures at 987 mbar pressure, and NO and ethene were added to the reactant mixtures to scavenge Cl atoms formed from the photolysis of CCl CHO. The concentrations of CCl CHO and ethyl acetate were measured by 3 3 GC and/or FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CCl CHO)/k(HO + ethyl acetate) is placed −12 3 −1 −1 on an absolute basis by using a rate coefﬁcient of k(HO + ethyl acetate) = 1.6 × 10 cm molecule s (Atkinson, 1989). (b) HO radicals were generated by the photolysis of CH ONO or C H ONO in CH ONO (or C H ONO)-CCl CHO-toluene- 3 2 5 3 2 5 3 air mixtures at 987± 13 mbar pressure. The concentrations of CCl CHO and toluene were measured by GC and/or FTIR spectroscopy. The measured rate coefﬁcient ratio of k(HO + CCl CHO)/k(HO + toluene) is placed on an absolute basis −12 3 −1 −1 by using a rate coefﬁcient of k(HO + toluene) = 5.63× 10 cm molecule s at 298 K (Calvert et al., 2002). (c) HO radicals were generated by the photolysis of O in the presence of water vapor in O -H O-CCl CHO-2- 3 3 2 3 methylpropane-air mixtures at ∼1 bar pressure. The concentrations of CCl CHO and 2-methylpropane were measured by GC. The measured rate coefﬁcient ratio k(HO + CCl CHO)/k(HO + 2-methylpropane) = 0.45± 0.01 is placed on an −12 3 −1 −1 absolute basis by using a rate coefﬁcient of k(HO + 2-methylpropane) = 2.12 × 10 cm molecule s at 298 K (Atkinson, 2003). Preferred Values −13 3 −1 −1 k = 8.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.8× 10 exp(-240/T ) cm molecule s over the temperature range 230-420 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 200 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4340 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The absolute and relative rate study of Barry et al. (1994) supersedes the earlier studies of Nelson et al. (1990), Balestra-Garcia et al. (1992) and Scollard et al. (1993). The three independent determinations of the rate coefﬁcient by Barry et al. (1994) are all lower than the absolute 298 K rate coefﬁcient of Dob ´ e ´ et al. (1989), as is the most recent absolute room temperature rate coefﬁcient of Talukdar et al. (2001). The most recent and extensive study of Talukdar et al. (2001) obtains a room temperature rate coefﬁcient which agrees with the lowest of the previously reported 298 K rate coefﬁcients, these being the PLP-RF rate coefﬁcient of Balestra-Garcia et al. (1992) and the DF-EPR rate coefﬁcient of Barry et al. (1994). The temperature dependence of the rate coefﬁcient measured by Talukdar et al. (2001) is also signiﬁcantly smaller than that reported by Dob ´ e ´ et al. (1989). The potential exists for erroneously high measured rate coefﬁcients because of secondary reactions involving Cl atoms generated from the photolysis of CCl CHO, as well as for erroneously low measured rate coefﬁcients because of wall adsorption losses of CCl CHO. The concentrations of CCl CHO were measured by UV absorption at 213.9 nm before and 3 3 after the reaction cell in the Talukdar et al. (2001) study, and losses were shown to be of no importance (<2%). The preferred values are therefore based on the absolute rate coefﬁcients of Talukdar et al. (2001). References Atkinson, R.: J. Phys. Chem. Ref. Data, Monograph 1, 1, 1989. Atkinson, R.: Atmos. Chem. Phys., 3, 2233, 2003. Balestra-Garcia, C., Le Bras, G. and Mac Leod, H.: J. Phys. Chem., 96, 3312, 1992. Barry, J., Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Le Bras, G., Poulet, G., Teton, ´ S., Chichinin, A., Canosa-Mas, C. E., Kinnison, D. J., Wayne, R. P. and Nielsen, O. J.: Chem. Phys. Lett., 221, 353, 1994. Calvert, J. G., Atkinson, R., Becker, K. H., Kamens, R. M., Seinfeld, J. H., Wallington, T. J. and Yarwood, G.: The Mechanisms of Atmospheric Oxidation of Aromatic Hydrocarbons, Oxford University Press, New York, NY, 2002. Dob ´ e, ´ S., Khachatryan, L. A. and Berces, ´ T.: Ber. Bunsenges. Phys. Chem., 93, 847, 1989. Nelson, L., Shanahan, I., Sidebottom, H. W., Treacy, J. and Nielsen, O. J.: Int. J. Chem. Kinet., 22, 577, 1990. Scollard, D. J., Treacy, J. J., Sidebottom, H. W., Balestra-Garcia, C., Laverdet, G., LeBras, G., MacLeod, H. and Teton, ´ S.: J. Phys. Chem., 97, 4683, 1993. Talukdar, R. K., Mellouki, A., Burkholder, J. B., Gilles, M. K., Le Bras, G. and Ravishankara, A. R.: J. Phys. Chem. A, 105, 5188, 2001. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4341 IV.A2.144 HO + CH C(O)Cl→ H O + CH COCl 3 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −14 6.8× 10 298± 3 Nelson et al., 1984; 1990 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO in CH ONO-NO-CH C(O)Cl-CHCl (the reference 3 3 3 3 compound)-air mixtures at 987 mbar pressure. The concentrations of CH C(O)Cl and CHCl were monitored during 3 3 the experiments by GC. The measured rate coefﬁcient ratio of k(HO + CH C(O)Cl)/k(HO + CHCl )∼0.65 is placed on 3 3 −13 3 −1 −1 an absolute basis by use of a rate coefﬁcient of k(HO + CHCl ) = 1.05 × 10 cm molecule s at 298 K (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 6.8× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.3 at 298 K. Comments on Preferred Values The preferred 298 K rate coefﬁcient is based on the relative rate coefﬁcient studies of Nelson et al. (1984) and Nelson et al. (1990), using the data presented in Table I and Figure 2 of Nelson et al. (1984) and in Figure 5 of Nelson et al. (1990), which −15 are the same data-set. Note that Table I of Nelson et al. (1990) cites a rate coefﬁcient a factor of 7 lower [(9.1± 3.2)× 10 3 −1 −1 cm molecule s at 298± 3 K], inconsistent with the data presented in their Figure 5 and with the data presented in Nelson et al. (1984). References IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Nelson, L., Treacy, J. J. and Sidebottom, H. W.: Proceedings of the 3rd European Symposium on the Physico-Chemical Behavior of Atmospheric Pollutants, 1984; D. Riedel Pub. Co., Dordrecht, Holland, pp. 258-263, 1984. Nelson, L., Shanahan, I., Sidebottom, H. W., Treacy, J. and Nielsen, O. J.: Int. J. Chem. Kinet., 22, 577, 1990. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4342 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.145 HO + CHF OCHClCF → H O + CHF OCClCF (1) 2 3 2 2 3 → H O + CF OCHClCF (2) 2 2 3 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (2.1± 0.7)× 10 298 Brown et al., 1989; 1990 DF-RF −12 1.12× 10 exp[-(1280± 50)/T ] 250-430 Tokuhashi et al., 1999 PLP/FP/DF-LIF −14 (1.51± 0.05)× 10 298 −14 (1.7± 0.3)× 10 298 Langbein et al., 1999 PLP-UVA −13 4.5× 10 exp[-(940± 100)/T ] 293-393 Beach et al., 2001 DF-RF −14 (1.9± 0.2)× 10 293 Relative Rate Coefﬁcients −13 <3× 10 300± 3 McLoughlin et al., 1993 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO-NO-CHF OCHClCF -diethyl ether air mixtures at ∼1 bar 3 2 3 pressure. The concentrations of CHF OCHClCF and diethyl ether were measured by GC. The measured upper limit to 2 3 the rate coefﬁcient ratio k(HO + CHF OCHClCF )/k(HO + diethyl ether) is placed on an absolute basis by using a rate 2 3 −11 3 −1 −1 coefﬁcient of k(HO + diethyl ether) = 1.31× 10 cm molecule s at 300 K (Atkinson, 1994). Preferred Values −14 3 −1 −1 k = 1.5× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.1× 10 exp(-1280/T ) cm molecule s over the temperature range 250-430 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 250 K. Comments on Preferred Values The study of Tokuhashi et al. (1999) used samples of CHF OCHClCF puriﬁed by GC (99.999% purity as analyzed by GC), 2 3 and the 298 K rate coefﬁcients obtained using three independent techniques (PLP-LIF, FP-LIF and DF-LIF) were identical within the experimental errors. The room temperature rate coefﬁcients of Brown et al. (1989; 1990) are higher than the rate coefﬁcient of Tokuhashi et al. (1999), possibly in part because of the presence of reactive impurities in the CHF OCF CHFCl 2 2 sample used by Brown et al. (1989, 1990) [see Tokuhashi et al. (1999)]. The rate coefﬁcients of Beach et al. (2001) at 360 K and 393 K are in excellent agreement with the data of Tokuhashi et al. (1999). However, the 293 K rate coefﬁcient of Beach et al. (2001) is 25% higher than the 298 K rate coefﬁcient of Tokuhashi et al. (1999), which is in agreement with the absolute rate coefﬁcient of Langbein et al. (1999). The preferred values are those of Tokuhashi et al. (1999), with the uncertainty in the value of E/R being sufﬁcient to encompass the temperature dependence reported by Beach et al. (2001). The upper limit to the rate coefﬁcient measured by McLoughlin et al. (1993) is consistent with the preferred values. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4343 References Atkinson, R.: J. Phys. Chem. Ref. Data, Monograph 2, 1, 1994. Beach, S. D., Hickson, K. M., Smith, I. W. M. and Tuckett, R. P.: Phys. Chem. Chem. Phys., 3, 3064, 2001. Brown, A. C., Canosa-Mas, C. E., Parr, A. D., Pierce, J. M. T. and Wayne, R. P.: Nature, 341, 635, 1989. Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ., 24A, 2499, 1990. Langbein, T., Sonntag, H., Trapp, D., Hoffmann, A., Malms, W., Roth, ¨ E.-P., Mors, ¨ V. and Zellner, R.: Br. J. Anaesthesia, 82, 66, 1999. McLoughlin, P., Kane, R. and Shanahan, I.: Int. J. Chem. Kinet., 25, 137, 1993. Tokuhashi, K., Takahashi, A., Kaise, M. and Kondo, S.: J. Geophys. Res., 104, 18681, 1999. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4344 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.146 HO + CHF OCF CHFCl → H O + CHF OCF CFCl (1) 2 2 2 2 2 → H O + CF OCF CHFCl (2) 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (1.7± 0.5)× 10 302 Brown et al., 1989; 1990 DF-RF −14 (4.7± 0.7)× 10 422 −13 7.46× 10 exp[-(1230± 80)/T ] 250-430 Tokuhashi et al., 1999 PLP/FP/DF-LIF −14 (1.19± 0.06)× 10 298 −14 (1.2± 0.2)× 10 298 Langbein et al., 1999 PLP-UVA Relative Rate Coefﬁcients −13 <3× 10 300± 3 McLoughlin et al., 1993 RR (a) Comments (a) HO radicals were generated by the photolysis of CH ONO-NO-CHF OCF CHFCl-diethyl ether air mixtures at ∼1 bar 3 2 2 pressure. The concentrations of CHF OCF CHFCl and diethyl ether were measured by GC. The measured upper limit to 2 2 the rate coefﬁcient ratio k(HO + CHF OCF CHFCl)/k(HO + diethyl ether) is placed on an absolute basis by using a rate 2 2 −11 3 −1 −1 coefﬁcient of k(HO + diethyl ether) = 1.31× 10 cm molecule s at 300 K (Atkinson, 1994). Preferred Values −14 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 7.5× 10 exp(-1230/T ) cm molecule s over the temperature range 250-430 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 150 K. Comments on Preferred Values The study of Tokuhashi et al. (1999) used samples of CHF OCF CHFCl puriﬁed by GC (99.999% purity as analyzed by GC), 2 2 and the 298 K rate coefﬁcients obtained using three independent techniques (PLP-LIF, FP-LIF and DF-LIF) were identical within the experimental errors. The earlier measurements of Brown et al. (1989; 1990) at 302 K and 422 K are higher than the data of Tokuhashi et al. (1999), probably in part because of the presence of reactive impurities in the CHF OCF CHFCl 2 2 sample used by Brown et al. (1989; 1990) [see Tokuhashi et al. (1999)]. The 298 K rate coefﬁcients from the absolute rate studies of Tokuhashi et al. (1999) and Langbein et al. (1999) are in excellent agreement, and the preferred values are based on these two studies. The upper limit to the rate coefﬁcient measured by McLoughlin et al. (1993) is consistent with the preferred values. References Atkinson, R.: J. Phys. Chem. Ref. Data, Monograph 2, 1, 1994. Brown, A. C., Canosa-Mas, C. E., Parr, A. D., Pierce, J. M. T. and Wayne, R. P.: Nature, 341, 635, 1989. Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ., 24A, 2499, 1990. Langbein, T., Sonntag, H., Trapp, D., Hoffmann, A., Malms, W., Roth, ¨ E.-P., Mors, ¨ V. and Zellner, R.: Br. J. Anaesthesia, 82, 66, 1999. McLoughlin, P., Kane, R. and Shanahan, I.: Int. J. Chem. Kinet., 25, 137, 1993. Tokuhashi, K., Takahashi, A., Kaise, M. and Kondo, S.: J. Geophys. Res., 104, 18681, 1999. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4345 IV.A2.147 HO + CF CCl O → O + CF CCl O H 2 3 2 2 2 3 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Relative Rate Coefﬁcients −12 (1.9± 0.7)× 10 298 Hayman et al., 1994 LP-UVA (a) Comments (a) Laser ﬂash photolysis-UV absorption study of CF CCl -CH OH-O -N mixtures. The kinetic data were obtained by 3 3 3 2 2 analyzing two sets of transient decays for CF CCl O and HO radicals on the basis of a mechanism consisting of 10 3 2 2 2 reactions. Preferred Values −12 3 −1 −1 k = 1.9× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.3 at 298 K. Comments on Preferred Values While the above value of the rate coefﬁcient seems reasonable, it has been derived from the analysis of a complex chemical system and requires independent veriﬁcation to reduce the recommended error limits. It is interesting to note, by comparison with data for analogous halogenated RO radicals, that while the α-substitution of Cl appears to reduce the rate coefﬁcient slightly, the presence of the CF group causes a much larger reduction in the value of k. References Hayman, G. D., Jenkin, M. E., Murrells, T. P. and Johnson, C. E.: Atmos. Environ. 28A, 421, 1994. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4346 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.148 HO + CH ClO → CH ClO H + O (1) 2 2 2 2 2 2 → HC(O)Cl + H O + O (2) 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 3.26× 10 exp[(822± 63)/T ] 251-600 Catoire et al., 1994 FP-UVA (a) −12 (4.9± 0.6)× 10 298 Branching Ratios k /k = 0.27± 0.05 295 Wallington et al., 1996 UVP-FTIR (b) k /k = 0.73± 0.12 Comments (a) Flash photolysis-UV absorption study of Cl -CH Cl-CH OH-O -N mixtures at a total pressure of 1013 mbar. Kinetic 2 3 3 2 2 data were obtained by analyzing pairs of decay curves recorded at two monitoring wavelengths, with differing contribu- tions to the total absorption made by CH ClO and HO radicals. 2 2 2 (b) Steady-state photolysis of Cl -CH Cl-H -O -N mixtures at total pressures of 933 mbar with FTIR spectroscopic moni- 2 3 2 2 2 toring of the removal of CH Cl and formation of CH ClO H and HCOCl as a function of the initial concentration ratio 3 2 2 [H ]/[CH Cl]. 2 3 Preferred Values −12 3 −1 −1 k = 5.0× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 3.2× 10 exp(820/T ) cm molecule s over the temperature range 250-600 K. k /k = 0.3 k /k = 0.7 Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. 1 (k /k) =± 0.1 at 298 K. 1 (k /k) =± 0.15 at 298 K. Comments on Preferred Values The preferred branching ratios are based on the results of the product study of Wallington et al. (1996), which demonstrate the participation of both reaction channels, with channel (2) dominating at 298 K. This is fully consistent with previous studies of the oxidation of CH Cl (Sanhueza and Heicklen, 1975; Niki et al., 1980), in which near-quantitative formation of HCOCl was observed, even though CH ClO was believed to be partially removed by reaction with HO . Tentative observation of 2 2 2 CH ClO H at yields up to ca. 10% in these earlier studies is also consistent with the branching ratios reported by Wallington 2 2 et al. (1996). The preferred rate coefﬁcient values are based on the sole kinetics study of Catoire et al. (1994). These results indicate that the rate coefﬁcients of the reactions of CH ClO and CH O radicals with the HO radical at 298 K are similar, as are their 2 2 3 2 2 temperature dependences. This is in marked contrast to the self reactions of CH ClO and CH O radicals where chlorine 2 2 3 2 substitution greatly enhances the rate coefﬁcient. Conﬁrmation of the above data is required. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4347 References Catoire, V., Lesclaux, R., Lightfoot, P. D. and Rayez, M.-T.: J. Phys. Chem. 98, 2889, 1994. Niki, H., Maker, P. D., Savage, C. M. and Breitenbach, L. P.: Int. J. Chem. Kinet. 12, 1001, 1980. Sanhueza, E. and Heicklen, J.: J. Phys. Chem. 79, 7, 1975. Wallington, T. J., Hurley, M.D. and Schneider, W.F.: Chem. Phys. Lett. 251, 164, 1996. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4348 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.149 HO + CHCl O → CHCl O H + O (1) 2 2 2 2 2 2 → C(O)Cl + H O + O (2) 2 2 2 → HC(O)Cl + HOCl + O (3) Rate coefﬁcient data (k = k + k + k ) 1 2 3 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 5.6× 10 exp[(700± 64)/T ] 286-440 Catoire et al., 1996 FP-UVA (a) −12 (5.46± 0.77)× 10 300 Branching Ratios k /k = 0.71 295 Catoire et al., 1996 UVP-FTIR (b) k /k = 0.29 Comments (a) Flash photolysis of CHCl in the presence of CH OH-O -N mixtures at a total pressure of 1013 mbar. Decays in transient 3 3 2 2 absorption signals (with contributions from CHCl O and HO ) were recorded in the wavelength range 220 nm to 250 2 2 2 nm. k derived in conjunction with optimization of the rate coefﬁcient for the self-reaction of CHCl O , using a ﬁve 2 2 reaction mechanism. (b) Steady-state photolysis of Cl or F in the presence of CH Cl -H -O -N mixtures at a total pressure of 933 mbar with 2 2 2 2 2 2 2 FTIR spectroscopic monitoring of the removal of CH Cl and formation of HCOCl and COCl as a function of the initial 2 2 2 concentration ratio [H ]/[CH Cl ]. 2 2 2 Preferred Values −12 3 −1 −1 k = 5.9× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 5.6× 10 exp(700/T ) cm molecule s over the temperature range 280-440 K. k /k = 0.7 at 298 K. k /k = 0.3 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. 1 (k /k) =± 0.2 at 298 K. 1 (k /k) =± 0.1 at 298 K. Comments on Preferred Values The preferred branching ratios are based on the results of the product study of Catoire et al. (1996), which provide evidence for the participation of reaction channels (2) and (3), through observation of C(O)Cl and HC(O)Cl formation, respectively. No evidence for formation of the hydroperoxide, CHCl OOH, by channel (1) was obtained. The existence of an alternative channel forming O , OH and CHCl O (and therefore HC(O)Cl from CHCl O decomposition) could not be ruled out on the 2 2 2 basis of the product studies alone; but no evidence for a radical-forming channel was apparent from the kinetics measurements in the same study. The preferred rate coefﬁcient values are based on the sole kinetics study of Catoire et al. (1996). These results indicate that the rate coefﬁcients of the reactions of CH O , CH ClO , CHCl O and CCl O radicals with the HO radical at 298 K are 3 2 2 2 2 2 3 2 2 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4349 similar, as are their temperature dependences. This is in marked contrast to the self-reactions, for which chlorine substitution greatly enhances the rate coefﬁcient. Conﬁrmation of the above sole determination is required. References Catoire, V., Lesclaux, R., Schneider, W. F. and Wallington, T. J.: J. Phys. Chem. 100, 14356, 1996. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4350 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.150 HO + CF ClO → O + CF ClO H (1) 2 2 2 2 2 2 → O + COF + HOCl (2) 2 2 → O + FCOCl + HOF (3) Rate coefﬁcient data (k = k + k + k ) 1 2 3 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (3.4± 1.7)× 10 296 Hayman and Battin-Leclerc, 1995 LP-UVA (a) Comments (a) Flash photolysis of H O in the presence of CHF Cl-O -N mixtures at a total pressure of 1013 mbar. Decays in transient 2 2 2 2 2 absorption signals (with contributions from CF ClO and HO ) were recorded in the wavelength range 220 nm to 240 2 2 2 nm. k derived from simulations of the decay traces using a 10 reaction mechanism. Preferred Values −12 3 −1 −1 k = 3.4× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.5 at 298 K. Comments on Preferred Values While the above value of the rate coefﬁcient seems reasonable, it has been derived from the analysis of a complex chemical system and requires independent veriﬁcation to reduce the recommended error limits. The rate coefﬁcients for the reactions of HO with a number of halogenated peroxy radicals suggest that the presence of an α-F atom has a deactivating inﬂuence. Consistent with this, k is apparently somewhat lower than those for the corresponding −12 3 −1 −1 reactions of CH O , CH ClO , CHCl O and CCl O , which all lie in the range (5-6)× 10 cm molecule s . 3 2 2 2 2 2 3 2 References Hayman, G. and Battin-Leclerc, F.: J. Chem. Soc. Faraday Trans. 91, 1313, 1995. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4351 IV.A2.151 HO + CCl O → CCl O H + O (1) 2 3 2 3 2 2 → C(O)Cl + HOCl + O (2) 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 4.8× 10 exp[(706± 31)/T ] 298-374 Catoire et al., 1996 FP-UVA (a) −12 (4.9± 0.6)× 10 300 Branching Ratios k /k = 1.0 295 Catoire et al., 1996 UVP-FTIR (b) Comments (a) Flash photolysis of CCl in the presence of CH OH-O -N mixtures at a total pressure of 1013 mbar. Decays in transient 4 3 2 2 absorption signals (with contributions from CCl O and HO ) were recorded in the wavelength range 220 nm to 250 nm. 3 2 2 k derived from simulations of the decay traces using a six reaction mechanism. (b) Steady-state photolysis of Cl or F in the presence of CHCl -H -O -N mixtures at a total pressure of 933 mbar with 2 2 3 2 2 2 FTIR spectroscopic monitoring of the removal of CHCl and formation of C(O)Cl as a function of the initial concen- 3 2 tration ratio [H ]/[CH Cl ]. C(O)Cl was the only carbon-containing product observed, with a yield of 100% (within 2 2 2 2 experimental error) under all conditions. Preferred Values −12 3 −1 −1 k = 5.1× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 4.7× 10 exp(710/T ) cm molecule s over the temperature range 280-440 K. k /k = 1.0 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. +0.0 1 (k /k) = at 298 K. −0.1 Comments on Preferred Values The results of the product study of Catoire et al. (1996) are consistent with the reaction proceeding exclusively via channel (2). The preferred rate coefﬁcient values are based on the results of the same study, which is the only study of this reaction. These results indicate that the rate coefﬁcients of the reactions of CH O , CH ClO , CHCl O and CCl O radicals with the HO 3 2 2 2 2 2 3 2 2 radical at 298 K are similar, as are their temperature dependences. This is in marked contrast to the self-reactions, for which chlorine substitution greatly enhances the rate coefﬁcient. Conﬁrmation of the above sole determination is required. References Catoire, V., Lesclaux, R., Schneider, W. F. and Wallington, T. J.: J. Phys. Chem. 100, 14356, 1996. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4352 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.152 HO + CFCl CH O → O + CFCl CH O H (1) 2 2 2 2 2 2 2 2 → O + CFCl CHO + H O (2) 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (9.2± 4.6)× 10 296 Hayman and Battin-Leclerc, 1995 LP-UVA (a) Comments (a) Flash photolysis of H O in the presence of CFCl CH -O -N mixtures at a total pressure of 1013 mbar. Decays in 2 2 2 3 2 2 transient absorption signals (with contributions from CFCl CH O and HO ) were recorded in the wavelength range 220 2 2 2 2 nm to 240 nm. k derived from simulations of the decay traces using a 10 reaction mechanism. Preferred Values −12 3 −1 −1 k = 9.2× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.5 at 298 K. Comments on Preferred Values While the above value of the rate coefﬁcient seems reasonable, it has been derived from the analysis of a complex chemical system and requires independent veriﬁcation to reduce the recommended error limits. Within the uncertainty of the determina- tion, k is indistinguishable from that recommended for the reaction of HO with C H O , suggesting that the presence of the 2 2 5 2 CFCl group has only a minor inﬂuence on the reaction. References Hayman, G. and Battin-Leclerc, F.: J. Chem. Soc. Faraday Trans. 91, 1313, 1995. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4353 IV.A2.153 HO + CF ClCH O → O + CF ClCH O H (1) 2 2 2 2 2 2 2 2 → O + CF ClCHO + H O (2) 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (6.8± 3.4)× 10 296 Hayman and Battin-Leclerc, 1995 LP-UVA (a) Comments (a) Flash photolysis of H O in the presence of CF ClCH -O -N mixtures at a total pressure of 1013 mbar. Decays in 2 2 2 3 2 2 transient absorption signals (with contributions from CF ClCH O and HO ) were recorded in the wavelength range 220 2 2 2 2 nm to 240 nm. k derived from simulations of the decay traces using a 10 reaction mechanism. Preferred Values −12 3 −1 −1 k = 6.8× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.5 at 298 K. Comments on Preferred Values While the above value of the rate coefﬁcient seems reasonable, it has been derived from the analysis of a complex chemical system and requires independent veriﬁcation to reduce the recommended error limits. Within the uncertainty of the determina- tion, k is indistinguishable from that recommended for the reaction of HO with C H O , suggesting that the presence of the 2 2 5 2 CF Cl group has only a minor inﬂuence on the reaction. References Hayman, G. and Battin-Leclerc, F.: J. Chem. Soc. Faraday Trans. 91, 1313, 1995. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4354 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.154 NO + C HCl → products 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 4.0× 10 exp(-2030/T ) 278-368 Noremsaune et al., 1997 DF-Vis (a) −16 (4.43± 0.32)× 10 295 Relative Rate Coefﬁcients −16 (2.9± 0.2)× 10 298 Atkinson et al., 1987 RR (b) −16 (3.8± 0.4)× 10 298 Noremsaune et al., 1997 RR (c) −16 (4.7± 1.1)× 10 298 Noremsaune et al., 1997 RR (d) −16 (3.6± 0.9)× 10 298 Chew et al., 1998 RR (e) Comments (a) NO was generated by F + HNO and detected by optical absorption in a multi-pass cell. Experiments conducted under 3 3 pseudo-ﬁrst order conditions. (b) The relative decay rates of C HCl and C H were monitored in N O -NO -organic-air mixtures at one atmosphere total 2 3 2 4 2 5 2 pressure of air to obtain: k(NO + C HCl )/k(NO + C H ) = (1.37± 0.08). This rate coefﬁcient ratio was placed on an 3 2 3 3 2 4 −16 3 −1 −1 absolute basis using k(NO + C H ) = 2.1× 10 cm molecule s (IUPAC, current recommendation). 3 2 4 (c) NO was formed in the thermal decomposition of N O in mixtures containing C HCl and ethene as reference reactant 3 2 5 2 3 at total pressures of 1013 mbar N . The addition of ethane as a Cl atom scavenger had no effect. k(NO + C HCl )/k(NO 2 3 2 3 3 −16 + C H ) was measured to be (1.79 ± 0.18). This was placed on an absolute basis using k(NO + C H ) = 2.1 × 10 2 4 3 2 4 3 −1 −1 cm molecule s (IUPAC, current recommendation). (d) NO was formed in the thermal decomposition of N O in mixtures containing C HCl and C H Cl as reference reactant 3 2 5 2 3 2 3 at total pressures of 1013 mbar N . Addition of ethane as a Cl atom scavenger had no effect. k(NO + C HCl )/k(NO + 2 3 2 3 3 C H Cl) was measured to be (1.3± 0.04). This was placed on an absolute basis using k(NO + C H Cl) = (3.7± 0.8)× 2 3 3 2 3 −16 3 −1 −1 10 cm molecule s (Noremsaune et al., 1997). (e) NO was formed in the thermal decomposition of N O in mixtures containing C HCl and 2,3-dimethylbutane as ref- 3 2 5 2 3 erence reactant at total pressures of 990 mbar air. Depletion of reactants was monitored by GC-FID. Addition of ethane as Cl and OH atom scavenger. k(NO + C HCl )/k(NO + 2,3-dimethylbutane) was measured to be (0.82± 0.21). This 3 2 3 3 −16 3 −1 −1 was placed on an absolute basis using k(NO + 2,3-dimethylbutane) = 4.39× 10 cm molecule s . Preferred Values −16 3 −1 −1 k = 3.5× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 3.2× 10 exp(-2030/T ) cm molecule s over the temperature range 270-370 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 500 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4355 Comments on Preferred Values The preferred value is derived from the relative rate coefﬁcients measured by Atkinson et al. (1987) and Noremsaune et al. (1997) determined relative to ethene, and Chew et al. (1998) relative to 2,3-dimethybutane. The temperature dependence is based on the result of Noremsaune et al. (1997), the only measurement over a range of temperatures. Their A-factor has been modiﬁed to reproduce the recommended rate constant at 298 K. There are several product channels open, resulting in formation of trichloroepoxyethane, dichloracetylchloride, chloroformyl and carbonylchloride (Noremsaune et al., 1995; Perez-Casany et al., 2000). References Atkinson, R., Aschmann, S. M. and Goodman, M. A.: Int. J. Chem. Kinet., 19, 299, 1987. Chew, A. A., Atkinson, R. and Aschmann, S. M.: J. Chem. Soc. Faraday Trans., 94, 1083, 1998. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Noremsaune, I. M. W., Hjorth, J. and Nielsen, C. J.: J. Atmos. Chem., 21, 223, 1995. Noremsaune, I. M. W., Langer, S., Ljungstrom, ¨ E. and Nielsen, C. J.: J. Chem. Soc., Faraday Trans. 93, 525, 1997. Perez-Casany, M. P., Nebot-Gil, I. and Sanchez-Martin, J.: J. Phys. Chem. A, 104, 11340, 2000. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4356 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.155 NO + C Cl → products 3 2 4 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −17 (9.6± 8.1)× 10 295 Noremsaune et al., 1997 DF-Vis (a) Relative Rate Coefﬁcients −17 <5× 10 298 Atkinson et al., 1987 RR (b) −17 (8± 3)× 10 299 Noremsaune et al., 1997 RR (c) −17 4× 10 299 Noremsaune et al., 1997 RR (d) −16 <1.8× 10 298 Chew et al., 1998 RR (e) Comments (a) NO generated by F + HNO and detected by optical absorption in a multi-pass cell. Experiments conducted under 3 3 pseudo-ﬁrst order conditions. (b) Derived by monitoring the relative decay rates of C Cl and C H in N O -NO -organic-air mixtures at one atmosphere 2 4 2 4 2 5 2 total pressure of air. The observations yielded k(NO + C Cl )/k(NO + C H ) = < 0.25. This upper limit to the rate 3 2 4 3 2 4 −16 3 −1 −1 coefﬁcient ratio was placed on an absolute basis by use of k(NO + C H ) = 2.1× 10 cm molecule s (IUPAC, 3 2 4 current recommendation). (c) NO formed in the thermal decomposition of N O in mixtures containing C HCl and ethene as reference reactant at 3 2 5 2 3 total pressures of 1013 mbar N . Addition of ethane as Cl atom scavenger had no effect. k(NO + C Cl )/k(NO + 2 3 2 4 3 −16 3 C H ) was measured to be (0.39± 0.11). This was placed on an absolute basis using k(NO + C H ) = 2.1× 10 cm 2 4 3 2 4 −1 −1 molecule s (IUPAC, current recommendation). (d) NO formed in the thermal decomposition of N O in mixtures containing C Cl and C H Cl as reference reactant at 3 2 5 2 4 2 3 total pressures of 1013 mbar N . Addition of ethane as Cl atom scavenger had no effect. k(NO + C Cl )/k(NO + 2 3 2 4 3 −16 C H Cl) was measured to be 0.1. This was placed on an absolute basis using k(NO + C H Cl) = (3.7 ± 0.8) × 10 2 3 3 2 3 3 −1 −1 cm molecule s (Noremsaune et al. 1997). (e) NO formed in the thermal decomposition of N O in mixtures containing C Cl and 2,3-dimethylbutane as reference 3 2 5 2 4 reactant at total pressures of 990 mbar air. Depletion of reactants was monitored by GC-FID. Addition of ethane as Cl and OH atom scavenger. k(NO + C Cl )/k(NO + 2,3-dimethylbutane) was measured to be (0.21± 0.18). This was placed 3 2 4 3 −16 3 −1 −1 on an absolute basis using k(NO + 2,3-dimethylbutane) = 4.39× 10 cm molecule s . Preferred Values −16 3 −1 −1 k < 1× 10 cm molecule s at 298 K. Comments on Preferred Values The preferred value is derived from the relative rate coefﬁcients measured by Atkinson et al. (1987). The upper limit to the rate coefﬁcient has been increased to take into account the spread in the data. References Atkinson, R., Aschmann, S. M., and Goodman, M. A.: Int. J. Chem. Kinet., 19, 299, 1987. Chew, A. A., Atkinson, R. and Aschmann, S. M.: J. Chem. Soc. Faraday Trans., 94, 1083, 1998. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Noremsaune, I. M. W., Langer, S., Ljungstrom, ¨ E. and Nielsen, C. J.: J. Chem. Soc., Faraday Trans. 93, 525, 1997. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4357 IV.A2.156 ClO + CH O → ClOO + CH O (1) 3 2 3 → OClO + CH O (2) → HCHO + HCl + O (3) → CH Cl + O (4) 3 3 → CH OCl + O (5) 3 2 ◦ −1 1H (1) = 4.1 kJ·mol ◦ −1 1H (2) = 1.2 kJ·mol ◦ −1 1H (3) = -311.5 kJ·mol ◦ −1 1H (4) = -49.9 kJ·mol ◦ −1 1H (5) = -174.6 kJ·mol Rate coefﬁcient data (k = k + k + k + k + k ) 1 2 3 4 5 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (3.1± 1.7)× 10 300 Simon et al., 1989 MM-UVA (a) −12 3.25× 10 exp[-(114± 38)/T ] 225-355 Helleis et al., 1993 DF-MS (b) −12 2.22× 10 295 −12 (1.9± 0.4)× 10 293 Kenner et al., 1993 DF-MS (c) −12 2.0× 10 exp[(80± 50)/T ] 233-300 Kukui et al., 1994 DF-MS (d) −12 (2.5± 0.3)× 10 300 Branching Ratios k /k > 0.70 300 Simon et al., 1989 IR, UV (e) k /k < 0.05 k /k < 0.02 k /k = 1.51 exp[-(218± 93)/T ] 225-295 Helleis et al., 1993 DF-MS (f) k /k < 0.02 k /k = 0.08 exp[(377± 178)/T ] k /k = 0.50± 0.2 300 Kukui et al., 1994 DF-MS (g) k /k = 0.63± 0.2 273 k /k = 0.38± 0.2 253 k /k = 0.26± 0.1 233 k /k = 0.011 exp[(836± 140)/T ] 233-300 −1.65 k /k = (T /300) - 0.223 exp(411/T ) 215-295 Helleis et al., 1994 DF-MS (h) k /k = 0.21 - 0.51 298 Biggs et al., 1995 DF-LIF (i) k /k = 0.3± 0.1 298 Daele ¨ and Poulet, 1996 DF-LIF (j) Comments (a) Broad band photolysis of slowly ﬂowing Cl -Cl O-CH -O mixtures at 312± 7 mbar. CH O and ClO were detected by 2 2 4 2 3 2 absorption at 240 nm and 292.2 nm, respectively. The rate constant was derived by ﬁtting time dependent optical density measurements at 240 nm and 292.2 nm to a chemical model. (b) Flow tube at 2.3-4 mbar He. CH O formed in F + CH in the presence of O , ClO formed from Cl + Cl O, or Cl + OClO 3 2 4 2 2 or Cl + O . Both reactants were monitored at their parent ions by mass spectrometry, and the pseudo ﬁrst order decay of CH O in excess concentration of ClO used to derive k directly. 3 2 (c) Flow tube at 2.5 mbar He. CH O formed in F + CH in presence of O , ClO formed from Cl + O . Both reactants were 3 2 4 2 3 monitored at their parent ions by mass spectrometry, and the pseudo ﬁrst order decay of CH O in excess concentration 3 2 of ClO used to derive k directly. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4358 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry (d) Flow tube at 5–6 mbar He. CH O formed in F + CH in presence of O , ClO formed from Cl + O . Both reactants were 3 2 4 2 3 monitored at their parent ions by mass spectrometry, and the pseudo ﬁrst order decay of CH O in excess concentration 3 2 of ClO used to derive k directly. (e) FTIR and UV analysis of ﬂowing gas-mixture (as described in comment (a)). No evidence for OClO formation enabled the upper limit of k /k < 0.05 to be derived. Also, no evidence for O formation from channel (4). Observed products 2 3 by FTIR were HCHO, CH OH, HCl and HC(O)OH. HC(O)OH proﬁles were analysed with the assumption that it was formed in reactions of HCHO with HO which allows some differentiation between channels (1) and (3), both of which generate HCHO if O is present, but only one of which generates HO . The yield of HC(O)OH was compatible with k /k 2 2 > 0.7 and k /k < 0.3. (f) (see also comment b). Mass spectrometric detection of products. No evidence was found for formation of OClO, O or CH Cl, suggesting that channels 2 and 4 are unimportant. Use of CD O enabled sensitive measurement of DCl 3 3 2 formation, and an upper limit of 2% for channel 3. HCHO, HOCl and CH OCl were positively identiﬁed as products. Branching ratios were derived by assuming that CH OCl is formed directly in channel (5), whereas HCHO and HOCl arise from channel (1) followed by rapid reaction of CH O with ClO, and by calibrating the CH O and HCHO signals. 3 3 2 The branching ratio to channel (5) was derived by assuming that only channels (1) and (5) are signiﬁcant (i.e. sum to unity), though the predicted negative temperature dependence of the CH OCl yield was observed. (g) (see also comment d). CH O formed in F + CH in presence of O , ClO formed from Cl + O . No evidence found for 3 2 4 2 3 formation of OClO or CH Cl. Observed products were CH OCl, HOCl and HCHO. Branching ratios for CH OCl and 3 3 3 HCHO derived by quantitative mass spectrometric detection of both CH O loss and CH OCl or HCHO formation. The 3 2 3 parameterisation of the branching ratio k /k was derived by ﬁtting to the authors tabulated data. HOCl signals were also converted to temperature dependent values of k /k by normalising to (k + k )/k = 1 at 300 K. 1 1 5 (h) Flow tube at 2.3 mbar He. CH O formed in F + CH in presence of O , ClO formed from Cl + Cl O. Branching ratios 3 2 4 2 2 derived by quantitative mass spectrometric detection of both CH O loss and CH OCl formation. 3 2 3 (i) Flow tube at 2.7 mbar He. CH O (not detected) formed in F + CH in presence of O , ClO (detected by MS) formed 3 2 4 2 from Cl + O . CH O detected by LIF at 292.8 nm. Derivation of the branching ratio for channel (1) involved modelling 3 3 CH O proﬁles that were inﬂuenced by the presence of CH O impurity in the CH O source, and reactions of both CH O 3 3 3 2 3 2 and CH O with Cl atoms, and loss of CH O by reaction with ClO and at the wall. 3 3 (j) Flow tube at 1.3 mbar He. CH O formed in F + CH in presence of O , ClO (detected by MS) formed from Cl + O . 3 2 4 2 3 CH O was detected quantitatively by LIF at 298.3 nm, and CH OCl was observed but not quantiﬁed. As in comment (i), 3 3 derivation of the branching ratio required numerical simulation of several processes. Preferred Values −12 3 −1 −1 k = 2.2× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 2.4× 10 exp(-20/T ) cm molecule s over the temperature range 220-360 K. k /k = 0.73 at 298 K. k /k = 1.51 exp(-218/T ) from 220 to 300 K. k /k = 0.15 at 298 K. k /k = 0.018 exp(630/T ) from 220 to 300 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 200 K. 1 (k /k)=± 0.2 at 298 K. 1 (E/R) =± 150 K. 1 (k /k) = 0.1 at 298 K. 1 (E/R) =± 300 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4359 Comments on Preferred Values The preferred value of k at 298 K is the unweighted average k from the direct studies of Helleis et al. (1993), Kenner et al. (1993) and Kukui et al. (1994) who all measured the CH O radical directly by MS, under pseudo ﬁrst-order conditions. The 3 2 recommended value also encompasses the result of Simon et al. (1989), which was obtained indirectly, and is consistent with −12 3 −1 −1 the upper limit of k(200 K) < 4.0 × 10 cm molecule s set by DeMore (1991). The temperature dependence of k was derived by averaging the values of E/R presented by Helleis et al. (1993) and Kukui et al. (1994) and adjusting the pre-exponential factor to obtain the recommended value of k(298 K). Although there is consensus that formation of CH Cl, O , OClO and HCl are insigniﬁcant, (Simon et al., 1989; Helleis et al., 3 3 1993; Kenner et al., 1993; DeMore, 1991) ruling out channels (2-4), there is disagreement in the branching ratio to channels (1) and (5). The most reliable branching ratio is that to CH OCl formation (5), as CH OCl is easiest to calibrate, and is a 3 3 non-reactive product. The preferred branching ratio at 298 K for channel (5) is the averaged result of Helleis et al. (1993) and Kukui et al. (1994). The data of Helleis et al. (1993) are reproduced by the expression: k /k = 0.034 exp (430/T ), which was combined with k /k = 0.011 exp (836/T ) from Kukui et al. (1994) to obtain the preferred expression for the temperature dependence of branching to channel (5). There are two direct measurements (Biggs et al., 1995; Daele ¨ et al., 1996) of CH O formation in channel (1), which required extensive modelling of its further reactions, and which had to take its presence as impurity in the CH O source into account 3 2 (see comments i and j). There are also indirect measurements, which assume rapid conversion of CH O to HCHO and HOCl via reaction with the excess ClO, which is borne out in separate studies of the kinetics of this reaction (Daele ¨ et al. 1996, Biggs et al. 1995). Helleis et al. (1993) and Kukui et al. (1994) observed formation of both HCHO and HOCl, with kinetics consistent with formation in channel (1) as rate limiting step. Although only HCHO could be accurately calibrated, HOCl signals were consistent with expected ionization efﬁciencies compared to ClO. The data of Kukui et al. (1994) suffered from a large background under the HCHO peak, which introduced severe uncertainty into their measurement of k /k, and the preferred branching ratio for channel 1 at 298 K, and its temperature dependence is therefore taken from Helleis et al. (1993). This data is in excellent agreement with the values of k /k which Kukui et al. (1994) derived from HOCl signals and assuming that only channels (1) and (5) contribute at 300 K. When summed together, channels (1) and (5) are seen to represent 85–90 % of the overall reaction, although these measure- ments are associated with large errors that do not preclude a signiﬁcant, so far unconsidered reaction channel, which would potentially also explain the low branching ratios for CH O formation obtained. The error limits on k /k are expanded to ac- 3 1 commodate this. Theoretical work (Drougas et al., 2003) has shown that the reaction proceeds via formation of a CH OOOCl association complex on both a singlet surface (decomposing to CH O + ClOO, (1)) or a triplet surface (rearranging to form CH OCl + O (2)), which is consistent with experimental ﬁndings. 3 2 References Biggs, P., Canosa-Mas, C. E., Fracheboud, J.-M., Shallcross, D. E. and Wayne, R. P.: Geophys. Res. Lett. 22, 1221, 1995. Biggs, P., Canosa-Mas, C. E., Fracheboud, J.-M., Marston, G., Shallcross, D. E. and Wayne, R. P.: J. Chem. Soc. Faraday Trans. 91, 3045, 1995. Daele, ¨ V. and Poulet, G.: J. Chim. Phys. 93, 1081, 1996. Daele, ¨ V., Laverdet, G. and Poulet, G.: Int. J. Chem. Kinet. 28, 589, 1996. DeMore, W. B.: J. Geophys. Res. 96, 4995, 1991. Drougas, E., Jalbout, A. F. and Kosmas, A. M.: J. Phys. Chem. A 107, 11386, 2003. Helleis, F., Crowley, J. N. and Moortgat, G. K.: J. Phys. Chem. 97, 11464, 1993. Helleis, F., Crowley, J. and Moortgat, G.: Geophys. Res. Lett. 21, 1795, 1994. Kenner, R. D., Ryan, K. R. and Plumb, I. C.: Geophys. Res. Lett. 20, 1571, 1993. Kukui, A. S., Jungkamp, T. P. W. and Schindler, R. N.: Ber. Bunsenges. Phys. Chem. 98, 1298, 1994. Simon, F. G., Burrows, J. P., Schneider, W., Moortgat, G. K. and Crutzen, P. J.: J. Phys. Chem. 93, 7807, 1989. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4360 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.157 CF Cl + O + M→ CF ClO + M 2 2 2 2 ◦ −1 1H = -127.4 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −29 −5.2 1.4× 10 (T /298) [N ] 200-300 Forst and Caralp, 1991 (a) Comments (a) Microcanonical variational theory with inversion of partition functions, used for interpolation between experimental data of the reactions O + (CCl , CCl F and CF ). 2 3 2 3 Preferred Values −29 −5 3 −1 −1 k = 1.4× 10 (T /300) [N ] cm molecule s over the temperature range 200-300 K. 0 2 Reliability 1 log k =± 0.5 at 298 K. 1 n =± 3. Comments on Preferred Values There are no measurements for this reaction. However, the analysis by Forst and Caralp (1991), as well as a simple interpolation of k -values for CF + O and CFCl + O lead to the given preferred values. Unlike Forst and Caralp (1991), who prefer F 0 3 2 2 2 c = 0.6 we recommend F = 0.4. High-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 −0.56 7.1× 10 (T /298) 200-300 Forst and Caralp, 1991 (a) Comments (a) See comment (a) for k . Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4361 Preferred Values −12 −0.6 3 −1 −1 k = 7× 10 (T /298) cm molecule s over the temperature range 200-300 K. Reliability 1 log k =± 0.5 at 298 K. 1 n =± 0.5. Comments on Preferred Values See Comments on Preferred Values for k . References Forst, W. and Caralp, F.: J. Chem. Soc. Faraday Trans.. 87, 2307, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4362 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.158 CFCl + O + M→ CFCl O + M 2 2 2 2 ◦ −1 1H = -124.6 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −30 (5.0± 0.8)× 10 [N ] 298 Caralp and Lesclaux, 1983 PP-MS (a) −30 −6 5.5× 10 (T /298) [N ] 233-373 Danis, 1991 PLP-MS (b) Comments (a) Pulsed laser photolysis-MS study. Falloff curve measure over the range 0.3–16 mbar, extrapolated with F = 0.6 and k = c ∞ −12 3 −1 −1 6× 10 cm molecule s . (b) As comment (a). Results cited and evaluated by Forst and Caralp (1991). Preferred Values −30 −6 3 −1 −1 k = 6× 10 (T /298) [N ] cm molecule s over the temperature range 230-380 K. 0 2 Reliability 1 log k =± 0.3 at 298 K. 1 n =± 3. Comments on Preferred Values There are only measurements from a single laboratory which were made close to the low pressure limit of the falloff curve. Using F values of 0.35–0.4 such as observed for CCl + O and CF + O would only slightly modify the extrapolated values c 3 2 3 2 of k but be of larger inﬂuence on k . 0 ∞ High-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (6± 1)× 10 298 Caralp and Lesclaux, 1983 PLP-MS (a) −12 (9± 3)× 10 233-273 Danis, 1991 PLP-MS (b) Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4363 Comments (a) See comment (a) for k (b) See comment (b) for k Preferred Values −12 3 −1 −1 k = 9× 10 cm molecule s over the temperature range 230-300 K. Reliability 1 log k =± 0.3 at 298 K. 1 n =± 1. Comments on Preferred Values See Comments on Preferred Values for k . Using F = 0.4 instead of 0.6 in the present case would increase k by a factor of 0 c ∞ 1.5. The present choice, therefore, is based on the data from Caralp and Lesclaux (1983) and F ≈ 0.4. References Caralp, F. and Lesclaux, R.: Chem. Phys. Lett., 102, 54, 1983. Danis, F.: Ph. Thesis, Bordeaux 1990, cited by Forst and Caralp, 1991. Forst, W. and Caralp, F.: J. Chem. Soc. Faraday Trans., 87, 2307, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4364 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.159 CCl + O + M→ CCl O + M 3 2 3 2 ◦ −1 1H = -92 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −31 (5.8± 0.6)× 10 [He] 295 Ryan and Plumb, 1984 DF-MS (a) −30 −6.3 (1.6± 0.3)× 10 (T /298) [N ] 233-333 Danis et al., 1991 PLP-MS/UVA (b) −31 −6.1 (6.5± 0.2)× 10 (T /300) [N ] 298-333 Fenter et al., 1993 PLP-MS/UVA (c) −31 −8.7 (2.7± 0.2)× 10 (T /300) [He] 286-332 Nottingham et al., 1994 F-MS (d) −30 −6.3 (1.1± 0.3)× 10 (T /300) [N ] 260-346 Luther et al., 2001 PLP-UVA (e) −31 −6.9 (4.2± 0.7)× 10 (T /298) [He] Comments (a) Microwave discharge ﬂow-quadrupole MS study. CCl radicals generated by the reaction F + CHCl → CCl + HF. 3 3 3 Falloff curve studied between 2.3 and 7 mbar of He and extrapolated with F = 0.25. (b) Laser photolysis of CCl with MS detection at lower and UV absorption detection at higher pressures. Measurements between 1 and 16 mbar as well as at 930 mbar of N . Evaluation with F = exp(-T /255), i.e., F = 0.31 at 300 K, and k 2 c c ∞ −12 3 −1 −1 = 3.2× 10 cm molecule s at 298 K. (c) Photolysis of CCl Br at 248 nm with detection of CCl by MS or UV absorption at 215 nm. Measurements at 1.3–16 3 3 mbar (MS detection) and 27–930 mbar (UV absorption detection). Falloff curve represented with F = 0.6 and k = 2.6 c ∞ −12 −1.1 3 −1 −1 × 10 exp(T /300) cm molecule s . (d) Flow tube using dissociative electron attachment for radical production and MS for radical detection. Pressures of He −12 3 −1 −1 below 4 mbar. Measurements evaluated with F = 0.33 and k = 2.74× 10 cm molecule s at 286 K. c ∞ (e) Photolysis of CCl Br at 248 nm and detection of CCl at 223.5 nm. Measurements at 200, 300, and 346 K over the 3 3 −0.35 −12 pressure range 2–900 bar in He and N . Data represented with F (N ) = 0.35 (T /300) and k = 5.2 × 10 2 c 2 ∞ −1.4 3 −1 −1 (T /300) cm molecule s . Preferred Values −30 −6.2 3 −1 −1 k = 1.1× 10 (T /300) [N ] cm molecule s over the temperature range 230-350 K. 0 2 Reliability 1 log k =± 0.2 at 298 K. 1 n =± 1. Comments on Preferred Values The preferred values are the average of the data from Danis et al. (1991) and Fenter et al. (1993) which are consistent with the falloff extrapolation from Luther et al. (2001). As the experiments were conducted to sufﬁciently low pressures, the different F -values used are of no relevance for the determination of k . c 0 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4365 High-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 5.1× 10 300 Cooper et al., 1980 PR-UVA (a) −12 2.5× 10 295 Ryan and Plumb, 1984 DF-MS (b) −12 −1.2 (3.2± 0.7)× 10 (T /298) 233-333 Danis et al., 1991 PLP-MS/UVA (c) −12 −1.1 (2.5± 0.2)× 10 (T /298) 298-333 Fenter et al., 1993 PLP-MS/UVA (d) −12 −1.4 (5.2± 0.2)× 10 (T /300) 260-346 Luther et al., 2001 PLP-UVA (e) Comments (a) Pulse radiolysis of CCl at 930 mbar of He. CCl O radicals detected by UV absorption. 4 3 2 (b) See comment (a) for k . (c) See comment (b) for k . (d) See comment (c) for k . (e) See comment (d) for k . Preferred Values −12 −1.4 3 −1 −1 k = 5.2× 10 (T /300) cm molecule s over the temperature range 260-350 K. Reliability 1 log k =± 0.3 at 298 K. 1 n =± 1.5. Comments on Preferred Values The combined data by Danis et al. (1991), Fenter et al. (1993) and Luther et al. (2001) at 300 K are well represented by a falloff curve with F = 0.35. Since the falloff curve has been measured up to very high pressures, the derived values from Luther et al. (2001) for k are preferred. The small temperature dependence of F employed by Luther et al. (2001) may be ∞ c neglected. References Cooper, R., Cumming, J. B., Gordon, S. and Mulac, W. A.: Rad. Phys. Chem., 16, 169, 1980. Danis, F., Caralp, F., Rayez, M. T. and Lesclaux, R.: J. Phys. Chem., 95, 7300, 1991. Fenter, F. F., Lightfoot, P. D., Niiranen, J. T. and Gutman, D.: J. Phys. Chem., 97, 5313, 1993. Luther, K., Oum, K. and Troe, J.: J. Phys. Chem. A, 105, 5535, 2001. Nottingham, W. C., Rudolph, R. N., Andrews, K. P., Moore, J. H. and Tossell, J. A.: Int. J. Chem. Kinet., 26, 749, 1994. Ryan, K. R. and Plumb, I. C.: Int. J. Chem. Kinet., 16, 59, 1984. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4366 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.160-192 R (R )CHO + O → R COR + HO (1) 1 2 2 1 2 2 R (R )CHO (+ M)→ products (2) 1 2 R = alkyl, halogenated alkyl, H or halogen atom. Rate coefﬁcient data 3 −1 Reaction Reactions k /k cm molecule Temp./K Reference Comments 1 2 Number IV.A2.160 CHFClO + O → COFCl + HO (1) k [O ] k (986 mbar,air) 298 Tuazon and Atkinson, 1993 (a) 2 2 1 2 2 IV.A2.161 CHFClO + M→ HCOF + Cl + M (2) IV.A2.162 CF ClO + O → products (1) k [O ] k (933 mbar,air) 298 Edney and Driscoll, 1992 (b) 2 2 1 2 2 IV.A2.163 CF ClO + M→ COF + Cl + M (2) k = 7.0× 10 298 Carr et al., 1986; FP-UVA 2 2 2 13 −1 k = 3× 10 exp(-5250/T )(k/s ) Rayez et al., 1987 IV.A2.164 CFCl O + O → products (1) k [O ] k (986 mbar,air) 298 Tuazon and Atkinson, 1993 (c) 2 2 1 2 2 IV.A2.165 CFCl O + M→ COFCl + Cl + M (2) k = 7.0× 10 Lesclaux et al., 1987; FP-MS 2 2 13 −1 k = 3× 10 exp(-5250/T )(k/s ) Rayez et al., 1987 IV.A2.166 CCl O + M→ COCl + Cl + M (2) k = 8.0× 10 Lesclaux et al., 1987; FP-MS(c) 3 2 2 13 −1 k = 4× 10 exp(-4600/T )(k/s ) Rayez et al., 1987 IV.A2.167 CF ClCH O + O → CF ClCHO + HO (1) k [O ] k (986 mbar,air) 298 Tuazon and Atkinson, 1994 (d) 2 2 2 2 2 1 2 2 IV.A2.168 CF ClCH O + M→ CF Cl + HCHO + M (2) 2 2 2 IV.A2.169 CFCl CH O + O → CFCl CHO + HO (1) k [O ] k (986 mbar,air) 298 Tuazon and Atkinson, 1994 (e) 2 2 2 2 2 1 2 2 −15 IV.A2.170 CFCl CH O + M→ CFCl + HCHO + M (2) k = 2.0× 10 298 Mors ¨ et al., 1996; (f) 2 2 2 1 −16 k = 1.3× 10 298 Wu and Carr, 1996 (g) −15 k = 2.4× 10 exp[-(944±55)/T ] 251-341 IV.A2.171 CF CFClO + O → products (1) k [O ] k (933 mbar,air) 298 Edney and Driscoll, 1992 (h) 3 2 1 2 2 IV.A2.172 CF CFClO + M→ CF COF + Cl + M (2) k [O ] k (986 mbar,air) 298 Tuazon and Atkinson, 1993 (i) 3 3 1 2 2 IV.A2.173 CF CCl O + O → products (1) k [O ] k (933 mbar,air) 298 Edney et al., 1991 (j) 3 2 2 1 2 2 IV.A2.174 CF CCl O + M→ CF COCl + Cl + M (2) k [O ] k (135 mbar,O ) 298 Sato and Nakamura, 1991 (k) 3 2 3 1 2 2 2 k [O ] k (986 mbar,air) 298 Tuazon and Atkinson, 1993 (l) 1 2 2 k [O ] k (∼ 1 bar,air) 298 Hayman et al., 1994 (m) 1 2 2 IV.A2.175 CF CF CCl O + O → products (1) k [O ] k (135 mbar,O ) 298 Sato and Nakamura, 1991 (n) 3 2 2 2 1 2 2 2 IV.A2.176 CF CF CCl O + M → CF CF COCl + Cl + (2) k [O ] k (986 mbar,air) 298 Tuazon and Atkinson, 1994 (o) 3 2 2 3 2 1 2 2 IV.A2.177 CF ClCF CFClO + O → products (1) k [O ] k (135 mbar,O ) 298 Sato and Nakamura, 1991 (p) 2 2 2 1 2 2 2 IV.A2.178 CF ClCF CFClO + M → CF ClCF COF + (2) k [O ] k (986 mbar,air) 298 Tuazon and Atkinson, 1994 (q) 2 2 2 2 1 2 2 Cl + M −18 IV.A2.179 CH ClO + O → HCOCl + HO (1) 4.6× 10 (933 mbar, O + N ) 296 Kaiser and Wallington, 1994 (r) 2 2 2 2 2 −12 IV.A2.180 CH ClO + M→ HCO + HCl + M (2) k = 1.3× 10 exp[-(934±128)/T ] 265-306 Wu and Carr, 2001 (s) 2 1 k = 7.7× 10 exp[-(4803±722)/T ] 265-306 (13 mbar) IV.A2.181 CH CHClO + O → CH COCl + HO (1) k [O ] k (933 mbar,air) 295 Shi et al., 1993 (t) 3 2 3 2 1 2 2 IV.A2.182 CH CHClO + M→ CH CO + HCl + M (2) k [O ] k (1013 mbar,air) 298 Maricq et al., 1993 (u) 3 3 1 2 2 IV.A2.183 HOCH CHClO + O → HOCH COCl + HCl (1) k [O ] k (986 mbar,air) 298 Tuazon et al., 1988 (v) 2 2 2 1 2 2 + HO IV.A2.184 HOCH CHClO + M → CH OH + HCOCl + (2) 2 2 IV.A2.185 HOCHClCH O + O → HOCHClCHO + (1) k [O ] k (986 mbar,air) 298 Tuazon et al., 1988 (v) 2 2 1 2 2 HO IV.A2.186 HOCHClCH O + M→ CHClOH + HCHO + (2) IV.A2.187 CH CCl O + O → products (1) k [O ] k (933 mbar, O ) 298 Nelson et al., 1990 (w) 3 2 2 1 2 2 2 IV.A2.188 CH CCl O + M→ CH COCl + Cl + M (2) 3 2 3 IV.A2.189 CCl CH O + O → CCl CHO + HO (1) k [O ] k (933 mbar, O ) 298 Nelson et al., 1990 (x) 3 2 2 3 2 1 2 2 2 IV.A2.190 CCl CH O + M→ CCl + HCHO + M (2) 3 2 3 IV.A2.191 CCl CCl O + O → products (1) k [O ] k 298 Sato and Nakamura, 1991 (y) 3 2 2 1 2 2 IV.A2.192 CCl CCl O + M→ CCl COCl + Cl + M (2) 3 2 3 Comments (a) Steady-state photolysis of Cl in the presence of CH FCl-air mixtures (986 mbar) with FTIR absorption spectroscopic 2 2 analyses: a 100% yield of HCOF was observed, consistent with k [O ] k . 1 2 2 (b) Steady-state photolysis of Cl in the presence of CHF Cl-air mixtures (933 mbar) with FTIR absorption spectroscopic 2 2 analysis: a 111 ± 6% yield of COF was observed, consistent with k [O ] k , The cited absolute values for k were 2 1 2 2 2 derived from evaluation of data of Carr et al. (1986) and Rayez et al. (1987) reported in IUPAC Supplement IV, 1992. (c) Similar experiments to those of Comment (a) at a total pressure of 986 mbar, but with CHFCl a 100% yield of COF was 2 2 observed, consistent with k [O ] k . The cited absolute values for k were derived from evaluation of data of Lesclaux 1 2 2 2 et al. (1987) and Rayez et al. (1987) reported in IUPAC Supplement IV, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4367 (d) Steady-state photolysis of Cl in the presence of CH CF Cl-air mixtures (986 mbar) with FTIR absorption spectroscopic 2 3 2 analyses: an∼ 100% yield of CF ClCHO was observed, consistent with k [O ] k . 2 1 2 2 (e) Steady-state photolysis of Cl in the presence of CH CFCl -air mixtures (986 mbar) with FTIR absorption spectroscopic 2 3 2 analysis: an∼ 100% yield of CFCl CHO was observed, consistent with k [O ] k . Experiments on this reaction were 2 1 2 2 also carried out by Edney and Driscoll (1992) and Tuazon and Atkinson (1993). (f) Direct time-resolved experiment using laser pulsed photolysis-laser long path absorption; CFCl CH O produced by 2 2 CFCl CH O + NO reaction. 2 2 2 (g) UV ﬂash photolysis of CFCl CH /N /O mixtures (13–50 mbar); growth and decay of CFCl CH O radicals in excess O 2 3 2 2 2 2 2 measured by time resolved MS. (h) Steady-state photolysis of Cl in the presence of CF CHFCl-air mixtures (1 atm) with FTIR absorption spectroscopic 2 3 analyses: a 100± 4% yield of CF C(O)F was observed, consistent with k [O ] k . 3 1 2 2 (i) Steady-state photolysis of Cl in the presence of CF CHFCl-air mixtures at 986 mbar total pressure with FTIR absorption 2 3 spectroscopic analyses: a 101± 1% yield of CF C(O)F was observed, consistent with k [O ] k . 3 1 2 2 (j) Steady-state photolysis of Cl in the presence of CF CHCl -air mixtures (933 mbar) with FTIR absorption spectroscopic 2 3 2 analyses: a∼ 100% yield of CF C(O)Cl was observed, consistent with k [O ] k . 3 1 2 2 (k) Similar experiments to those of Comment (j) at a total pressure of 133 mbar. The observed formation of CF C(O)Cl is consistent with k [O ] k . 1 2 2 (l) Similar experiments to those of Comment (i) at a total pressure of 986 mbar, but with CF CHCl : a 98% yield of 3 2 CF C(O)Cl was observed, consistent with k [O ] k . 3 1 2 2 (m) Steady-state photolysis of Cl in the presence of CF CHCl -air mixtures (∼ 1 atm) with broad-band UV absorption 2 3 2 analyses: a∼ 100% yield of CF C(O)Cl was observed, consistent with k [O ] k . 3 1 2 2 (n) Similar experiments to those of Comment (k) at a total pressure of 133 mbar. The observed formation of CF CF C(O)Cl 3 2 is consistent with k [O ] k . 1 2 2 (o) Steady-state photolysis of Cl in the presence of CF CF CHCl -air mixtures at 986 mbar with FTIR spectroscopic anal- 2 3 2 2 yses: a 100% yield of CF CF C(O)Cl was observed, consistent with k [O ] k . 3 2 1 2 2 (p) Steady-state photolysis of Cl in the presence of CHFClCF CF Cl-O mixtures (133 mbar) with FTIR spectroscopic 2 2 2 2 analyses: observed formation of CF ClCF C(O)F is consistent with k [O ] k . 2 2 1 2 2 (q) Steady-state photolysis of Cl in the presence of CF ClCF CHFCl-air mixtures (986 mbar) with FTIR spectroscopic 2 2 2 analysis: a 99% yield of CF ClCF C(O)F was observed, consistent with k [O ] k . 2 2 1 2 2 (r) Steady-state photolysis of Cl in the presence of CH Cl-O -N mixtures with FTIR absorption spectroscopic analysis of 2 3 2 2 HC(O)Cl, CO, HCl and CH ClOOH products. k /k based on yields of CO and HC(O)Cl, the latter being corrected for 2 1 2 secondary formation and removal. The ratio k /k was found to be markedly pressure dependent over the range 12 to 933 1 2 mbar, and the cited value refers to 700 Torr (933 mbar) total pressure. (s) UV ﬂash photolysis - time resolved MS. Pressure = 7–50 mbar; growth of HCOCl and HCl products used to determine kinetics. (t) Steady-state photolysis of Cl in the presence of C H Cl-O -N mixture with FTIR spectroscopic analysis of products: 2 2 5 2 2 the observed high yields of HCl (157%) and CO (53%) were explained by reaction (2). (u) Laser ﬂash photolysis of Cl in the presence of C H Cl-air mixtures with infrared absorption detection of HCl. The 2 2 5 observed secondary formation of HCl was explained by reaction (2). (v) Steady-state photolysis of CH ONO or C H ONO in the presence of chloroethene -NO-air mixtures, with and without 3 2 5 C H as an added Cl atom scavenger. FTIR spectroscopic analysis of HCHO and HCOCl products, with close to unit 2 6 yields of each. These products and their formation yields are consistent with the qualitative relative values of k [O ] and 1 2 k shown above. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4368 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry (w) Steady-state photolysis of CH CCl -O mixtures in the presence of Br or NO (to scavenge Cl atoms), with GC and IR 3 3 2 2 analyses of products. CH COCl was the major product observed, consistent with the relative values of k [O ] and k 3 1 2 2 shown above. (x) Steady-state photolysis of Cl in the presence of CH CCl -O mixtures with GC and IR analyses of CCl CHO and COCl , 2 3 3 2 3 2 which are consistent with the relative values of k [O ] and k shown above. 1 2 2 (y) Steady-state photolysis of Cl in the presence of CHCl CCl -O mixtures (133 mbar) with FTIR spectroscopic analysis. 2 2 3 2 The observed formation yields of CCl COCl and COCl are consistent with k [O ] k . 3 2 1 2 2 Preferred Values R (R )CHO = CH ClO 1 2 2 −18 3 −1 k /k = 4.6× 10 cm molecule at 298 K. 1 2 Comments on Preferred Values R (R )CHO = CH ClO, CH CHClO 1 2 2 3 The elimination of HCl occurs from the CH CHClO radical (Shi et al., 1993, Maricq et al., 1993) as well as from the CH ClO 3 2 radical (Kaiser and Wallington, 1994; Wu and Carr, 2001). R (R )CHO = other radicals in the above table. 1 2 For the purpose of atmospheric modeling studies it is recommended that the above qualitative information on the ratios k /k be 1 2 used to decide if one or other of the alkoxy radical reaction pathways predominates or if both pathways should be considered. References Carr, R. W. Jr., Peterson, D. G. and Smith, F. K.: J. Phys. Chem., 90, 607, 1986. Edney, E. O. and Driscoll, D. J.: Int . J. Chem. Kinet., 24, 1067, 1992. Edney, E. O., Gay, B. W. and Driscoll, D. J.: J. Atmos., Chem., 12, 105, 1991. Hayman, G. D., Jenkin, M. E., Murrells, T. P. and Johnson, C. E.: Atmos. Environ., 28A, 421, 1994. Kaiser, E. W. and Wallington, T. J.: J. Phys. Chem., 98, 5679, 1994. Lescaux, R., Dognon, A. M. and Caralp, F.: J. Photochem. Photobiol. A: Chem., 41, 1, 1987. Maricq, M. M., Shi, J., Szente, J. J., Rimai, L. and Kaiser, E. W.: J. Phys. Chem., 97, 9686, 1993. Mors, ¨ V., Hoffmann, A., Malms, W. and Zellner, R.: Ber. Bunsenges. Phys. Chem., 100, 540, 1996. Nelson, L., Shanahan, I., Sidebottom, H. W., Treacy, J. and Nielsen, O. J.: Int. J. Chem. Kinet., 22, 577, 1990. Rayez, J. C., Rayez, M. T., Halvick, P., Duguay, B. and Lesclaux, R.: Chem. Phys., 116, 203, 1987. Sato, H. and Nakamura, T.: Nippon Kagaku Kaishi, 548, 1991. Shi, J., Wallington, T. J. and Kaiser, E. W.: J. Phys. Chem., 97, 6184, 1993. Tuazon, E. C. and Atkinson, R.: J. Atmos. Chem., 17, 179, 1993. Tuazon, E. C. and Atkinson, R.: Environ. Sci. Technol., 28, 2306, 1994. Tuazon, E. C., Atkinson, R., Aschmann, S. M., Goodman, M. A. and Winer, A. M.: Int. J. Chem. Kinet., 20, 241, 1988. Wu, F and Carr, R. W.: J. Phys. Chem. A 100, 9352, 1996. Wu, F and Carr, R. W.: J. Phys. Chem. A 105, 1423, 2001. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4369 IV.A2.193-202 RO + NO → RO + NO (1) 2 2 RO + NO + M → RONO + M (2) 2 2 (R= CH Cl, CHFCl, CF Cl, CFCl , CCl , CH CFCl, CF ClCH , CFCl CH , CF CCl ,CH ClCH ) 2 2 2 3 3 2 2 2 2 3 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 Reaction k/cm molecule s Temp./K Reference Technique/Comments Number Absolute Rate Coefﬁcients IV.A2.193 R=CH Cl −11 (1.87± 0.20)× 10 295 Sehested et al., 1993 PR-AS (a) IV.A2.194 R = CHFCl −11 (1.31± 0.20)× 10 299 Bhatnagar and Carr, 1996 FP-MS (b) IV.A2.195 R=CF Cl −11 −(1.5±0.4) 1.6× 10 (T /298) 230-430 Dognon et al., 1985 PLP-MS (c) −11 (1.6± 0.3)× 10 298 −11 (1.31± 0.12)× 10 295 Sehested et al., 1993 PR-AS (a) IV.A2.196 R=CFCl −11 (1.6± 0.2)× 10 298 Lesclaux and Caralp, 1984 PLP-MS (d) −11 −(1.3±0.2) 1.45× 10 (T /298) 230-430 Dognon et al., 1985 PLP-MS (c) −11 (1.45± 0.2)× 10 298 IV.A2.197 R=CCl −11 (1.86± 0.28)× 10 295 Ryan and Plumb, 1984 DF-MS (e) −11 −(1.0±0.2) 1.7× 10 (T /298) 230-430 Dognon et al., 1985 PLP-MS (c) −11 (1.7± 0.2)× 10 298 IV.A2.198 R=CH CFCl −11 −(1.8±0.3) 2.0× 10 (T /300) 263-321 Wu and Carr, 1996 FP-MS (f) −11 1.9× 10 298 IV.A2.199 R=CF ClCH 2 2 −11 (1.18± 0.10)× 10 295 Sehested et al., 1993 PR-AS (a) IV.A2.200 R=CFCl CH 2 2 −11 (1.28± 0.11)× 10 295 Sehested et al., 1993 PR-AS (a) −11 −(1.5±0.2) 1.3× 10 (T /300) 263-321 Wu and Carr, 1996 FP-MS (f) −11 1.25× 10 298 IV.A2.201 R=CF CCl 3 2 −11 (1.5–2.0)× 10 298 Hayman et al., 1994 PLP-AS (g) IV.A2.202 R=CH ClCH 2 2 −12 (9.7± 1.2)× 10 298 Patchen et al., 2005 DF-CIMS (h) Comments (a) k determined from +d [NO ]/dt at a total pressure of 1 bar. (b) Photolysis of Cl in the presence of CH FCl, O , N and NO at 8–33 mbar total pressure. k was obtained from the 2 2 2 2 formation kinetics of NO . k was independent of pressure in the studied range. (c) No signiﬁcant pressure dependence in k over the range 1.3–13 mbar was observed. (d) Measurements were made at 2.7 mbar total pressure. (e) k independent of pressure over the range 2.3–7.2 mbar. (f) Photolysis of CH CFCl in the presence of O , N and NO at 11–27 mbar total pressure. k for both CH CFClO and 3 2 2 2 3 2 CFCl CH O were extracted simultaneously from the removal kinetics of NO and formation kinetics of CFCl CH O. k 2 2 2 2 2 was independent of pressure in the studied range. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4370 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry (g) k derived from computer ﬁt of transient absorption traces based on a mechanism of 9 reactions. Experiments performed at 1 bar pressure. (h) CH ClCH O generated from the C H + Cl reaction, with k determined from pseudo-ﬁrst order decay CH ClCH O in 2 2 2 2 4 2 2 2 the presence of NO. Measurements made at 130 mbar pressure. Preferred Values R = CH Cl −11 3 −1 −1 k = 1.9× 10 cm molecule s at 298 K. 1 log k =± 0.3 at 298 K. R = CHFCl −11 3 −1 −1 k = 1.3× 10 cm molecule s at 298 K. 1 log k =± 0.3 at 298 K. R = CF Cl −11 −1.5 3 −1 −1 k = 1.5× 10 (T /298) cm molecule s over the temperature range 230-430 K. 1 log k =± 0.2 at 298 K. 1n =±0.5. R = CFCl −11 −1.3 3 −1 −1 k = 1.5× 10 (T /298) cm molecule s over the temperature range 230-430 K. 1 log k =± 0.2 at 298 K. 1n =±0.5. R = CCl −11 −1.0 3 −1 −1 k = 1.8× 10 (T /298) cm molecule s over the temperature range 230-430 K. 1 log k =± 0.2 at 298 K. 1n =±0.5. R = CH CFCl −11 −1.8 3 −1 −1 k = 2.0× 10 (T /298) cm molecule s over the temperature range 260-320 K. 1 log k =± 0.3 at 298 K. 1n =±0.5. R = CF ClCH 2 2 −11 3 −1 −1 k = 1.2× 10 cm molecule s at 298 K. 1 log k =± 0.3 at 298 K. R = CFCl CH 2 2 −11 −1.5 3 −1 −1 k = 1.3× 10 (T /298) cm molecule s over the temperature range 260-320 K. 1 log k =± 0.2 at 298 K. 1n =±0.5. R = CF CCl 3 2 −11 3 −1 −1 k = 1.8× 10 cm molecule s at 298 K. 1 log k =± 0.3 at 298 K. R = CH ClCH 2 2 −12 3 −1 −1 k = 9.7× 10 cm molecule s at 298 K. 1 log k =± 0.3 at 298 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4371 Comments on Preferred Values R = CF ClCH , CH Cl 2 2 2 The preferred values are the rounded-off rate coefﬁcients determined by Sehested et al. (1993). R = CHFCl The preferred value is the rounded-off rate coefﬁcient determined by Bhatnagar and Carr (1996). R = CF Cl The preferred values are based on the temperature dependent data of Dognon et al. (1985), adjusted to ﬁt the average value of k from the data of Sehested et al.(1993) and Dognon et al. (1985). R = CFCl The preferred values are based on the temperature dependent data of Dognon et al. (1985), adjusted to ﬁt the average value of k from the data of Lesclaux and Caralp (1984), and Dognon et al. (1985). R = CH CFCl The preferred values are based on the temperature dependent data of Wu and Carr (1996). R = CFCl CH 2 2 The preferred value is the rounded-off average of the rate coefﬁcients determined by Sehested et al. (1993) and Wu and Carr (1996). R = CF CCl 3 2 The preferred value is the mid-point of the range of values determined by Hayman et al. (1994). R = CH ClCH 2 2 The preferred value is the rate coefﬁcient determined by Patchen et al. (2005). R = CCl The preferred values are based on the temperature dependent data of Dognon et al. (1985), adjusted to ﬁt the average value of k from the data of Ryan and Plumb (1984) and Dognon et al. (1985). The temperature dependence expressions are given in the form favoured by Dognon et al. (1985), and subsequently adopted by others, which best describe the measured data. Comparison of the reported rate coefﬁcients with those for the corresponding alkyl peroxy radicals, CH O and C H O , indicates that the presence of a α-halogen substituent typically enhances k 3 2 2 5 2 298 by a factor of about 1.5–2, with the reactions also possessing a similar dependence on temperature where comparison is possible. Although not so marked, it appears that additional α-halogen substituents result in further slight enhancements to k . Similarly to small alkyl peroxy radicals, the observations indicate that the reactions are dominated by the RO-forming channel (1). Dognon et al. (1985) measured quantum yields for NO greater than unity for all the RO radicals studied; 2 2 suggesting that the RO + NO reactions mainly form RO and NO , with additional NO being produced from secondary 2 2 2 chemistry. Nishida et al. (2004) have observed formation of a small yield 1.7 ± 0.3% of CF ONO from the reaction of 3 2 CF O with NO, conﬁrming the existence of channel (2) at 930 mbar pressure. This suggests that the reactions of the C 3 2 1 and C halogenated RO radicals will generally have minor channels forming RONO , but additional studies are required to 2 2 2 conﬁrm this. References Bhatnagar, A. and Carr, R.W.: Chem. Phys. Lett. 258, 651, 1996. Dognon, A. M., Caralp, F. and Lesclaux, R.: J. Chim. Phys. 82, 349, 1985. Hayman, G. D., Jenkin, M. E., Murrells, T. P. and Johnson, C. E.: Atmos. Environ. 28A, 421, 1994. Lesclaux, R. and Caralp, F.: Int. J. Chem. Kinet. 16, 1117, 1984. Patchen, A. K., Pennino, M. J. and Elrod, M. J.: J. Phys. Chem. A 109, 5865, 2005. Ryan, K. R. and Plumb, I. C.: Int. J. Chem. Kinet. 16, 591, 1984. Sehested, J., Nielsen, O. J., and Wallington, T. J.: Chem. Phys. Lett. 213, 457, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4372 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.203 CF ClO + NO + M→ CF ClO NO + M 2 2 2 2 2 2 ◦ −1 1H = -107 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −29 (3.8± 1.8)× 10 [O ] 298 Moore and Carr, 1990 FP-MS (a) −29 −6.2 (5.0± 1.0)× 10 (T /298) [O ] 248-324 Wu and Carr, 1991 FP-MS (b) Comments (a) CF ClO radicals generated by ﬂash photolysis of CF ClBr in the presence of O and detected by MS. Measurements 2 2 2 2 −12 3 −1 −1 over the pressure range 1.3–13 mbar, extrapolated with F = 0.6 and k = 5.2× 10 cm molecule s at 298 K. c ∞ −12 −2.5 3 −1 −1 (b) As comment (a). F = 0.78 exp(-T /569), i. e., F (298) = 0.46, and k = 4.5× 10 (T /298) cm molecule s c c ∞ used for extrapolation. Preferred Values −29 −6.2 3 −1 −1 3 k = 5× 10 (T /298) [N ] cm molecule s cm over the temperature range 250–320 K. 0 2 Reliability 1 log k =± 0.3 at 298 K. 1 n =± 2. Comments on Preferred Values The pressure dependence in the investigated pressure range ﬁts well to that observed at higher pressures for the reverse disso- ciation by Koppenkastrop ¨ and Zabel (1991) and the theoretical modellings by Destriau and Troe (1990) and by Caralp et al. (1988). Uncertainties of the used F = 0.46 at 298 K do not much inﬂuence the values of the derived k . Therefore the values c 0 from Wu and Carr (1991) are our preferred values, assuming equal values of k for the bath gases O and N . 0 2 2 High-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 5.2× 10 298 Moore and Carr, 1990 (a) −12 −2.5 4.5× 10 (T /298) 248-324 Wu and Carr, 1991 (b) Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4373 Comments (a) See comment (a) for k . (b) See comment (b) for k . The measurements were performed so far from the high pressure range that extrapolations were uncertain. Preferred Values −12 −0.7 3 −1 −1 k = 6.3× 10 (T /298) cm molecule s over the temperature range 250-320 K. Reliability 1 log k =± 0.3 at 298 K. 1 n =± 0.5. Comments on Preferred Values The unusually large negative temperature coefﬁcient of k derived by Wu and Carr (1991) signals problems with the falloff extrapolations. For this reason it appears safer to employ the falloff curves for CF ClO NO dissociation from Koppenkastrop ¨ 2 2 2 and Zabel (1991), which were studied over a ten times larger pressure range extending up to higher pressures. Doing this, the preferred value is derived which is consistent with our preferred data for CF O + NO . As for the reverse reaction, F = 0.30 3 2 2 c is recommended. References Caralp, F., Lesclaux, R., Rayez, M.-T., Rayez, J.-C. and Forst, W.: J. Chem. Soc. Faraday Trans. 2, 84, 569, 1988. Destriau, M. and Troe, J.: Int. J. Chem. Kinet., 22, 915, 1990. Koppenkastrop, ¨ D. and Zabel, F.: Int. J. Chem. Kinet., 23, 1, 1991. Moore, S. M. and Carr, R. W.: J. Phys. Chem., 94, 1393, 1990. Wu, F. and Carr, R. W.: Int. J. Chem. Kinet., 23, 701, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4374 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.204 CF ClO NO + M→ CF ClO + NO + M 2 2 2 2 2 2 ◦ −1 1H = 107 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data −1 k /s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −3 1.8× 10 exp(-10500/T ) [N ] 273–288 Koppenkastrop ¨ and Zabel, 1991 (a) −3 1.1× 10 exp(-10762/T ) [N ] 276-289 Xiong and Carr, 1994 (b) Comments (a) Thermal decomposition of CF ClO NO in a temperature-controlled (± 0.1 C) 420 liter reaction chamber. The reac- 2 2 2 tant was monitored in situ by long-path IR absorption. N pressures of 11, 82, and 800 mbar were employed. Falloff 16 −1 extrapolations with F = 0.30 and k = 1.6× 10 exp(-11990/T ) s . c ∞ (b) Continuous-ﬂow temperature-controlled (± 1 C) photoreactor coupled to MS. N pressures of 4–53 mbar were employed. 16 −1 Falloff extrapolations made with F = 0.45 and k = 6.7× 10 exp(-11871/T ) s . c ∞ Preferred Values −3 −1 k = 1.8× 10 exp(-10500/T ) [N ] s over the temperature range 270–290 K. 0 2 Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The measurements of Koppenkastrop ¨ and Zabel (1991) and of Xiong and Carr (1994) differ markedly in their pressure de- pendences which is reﬂected by large differences of the extrapolated k . As the pressure dependence observed by Xiong and Carr (1994) is much larger than given by theoretical falloff curves from Destriau and Troe (1990) and Caralp et al. (1988), the measurements by Xiong and Carr (1994) have to be in error for some unknown reason and are not considered here. Instead, the results from Koppenkastrop ¨ and Zabel (1991), which were obtained over a ten times larger pressure range, here are preferred with F = 0.30 and k such as given below. c ∞ High-pressure rate coefﬁcients Rate coefﬁcient data −1 k /s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients 1.6× 10 exp(-11990/T ) 273-288 Koppenkastrop ¨ and Zabel, 1991 (a) 6.7× 10 exp(-11871/T ) 276-289 Xiong and Carr, 1994 (b) Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4375 Comments (a) See comment (a) for k . (b) See comment (b) for k . The given value for k actually stems from a combination of recombination data, equilibrium 0 ∞ constants and theoretical modelling. It is consistent with the observed pressure dependence. Preferred Values 16 −1 k = 1.6× 10 exp(-11990/T ) s over the temperature range 270-290 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values See Comments on Preferred Values of k . References Caralp, F., Lesclaux, R., Rayez, M.-T., Rayez, J.-C. and Forst, W.: J. Chem. Soc. Faraday Trans. 2, 84, 569, 1988. Destriau, M. and Troe, J.: Int. J. Chem. Kinet., 22, 915, 1990. Koppenkastrop, ¨ D. and Zabel, F.: Int. J. Chem. Kinet., 23, 1, 1991. Xiong, J. Q. and Carr, R. W.: J. Phys. Chem., 98, 9811, 1994. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4376 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.205 CFCl O + NO + M→ CFCl O NO + M 2 2 2 2 2 2 ◦ −1 1H = -107 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k /cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −29 (3.5± 0.5)× 10 [O ] 298 Lesclaux and Caralp, 1984 PLP-MS (a) −29 −4.1 (3.5± 0.5)× 10 (T /298) [O ] 233-373 Lesclaux et al., 1986 PLP-MS (b) −29 −5.5 (5.5± 1.6)× 10 (T /298) [O ] 233-373 Caralp et al., 1988 PLP-MS (c) Comments (a) Pulsed laser photolysis with MS detection of CFCl O . Pressure range 1.3–13 mbar. Falloff extrapolation with F = 0.6 2 2 c −12 3 −1 −1 and k = 6.0× 10 cm molecule s . −12 −0.72 3 −1 −1 (b) As comment (a). Falloff extrapolation with F = 0.6 and k = 5.9× 10 (T /298) cm molecule s . c ∞ −12 −0.66 (c) As comment (a). Falloff extrapolation using F = exp(-T /342), i.e. F = 0.42 at 298 K, and k = 8.3× 10 (T /298) c c ∞ 3 −1 −1 cm molecule s . Preferred Values −29 −5.5 3 −1 −1 k = 5.5× 10 (T /298) [N ] cm molecule s over the temperature range 230–380 K. 0 2 Reliability 1 log k =± 0.3 at 298 K. 1 n =± 2. Comments on Preferred Values The data from Caralp et al. (1988) are preferred because they employ a value of F = 0.42. However, this value should be used independent of the temperature. Equal values of k for the bath gases O and N are assumed. 0 2 2 High-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k / cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (6.0± 1.0)× 10 298 Lesclaux and Caralp, 1984 (a) −12 −0.72 (5.9± 1.0)× 10 (T /298) 233-373 Lesclaux et al., 1986 (b) −12 −0.66 (8.3± 1.0)× 10 (T /298) 233-373 Caralp et al., 1988 (c) Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4377 Comments (a) See comment (a) for k . (b) See comment (b) for k . (c) See comment (c) for k . Preferred Values −12 −0.66 3 −1 −1 k = 8.3× 10 (T /298) cm molecule s over the temperature range 230-380 K. Reliability 1 log k =± 0.2 at 298 K. 1 n =± 0.5. Comments on Preferred Values See Comments on Preferred Values for k . References Caralp, F., Lesclaux, R., Rayez, M.-T., Rayez, J.-C. and Forst, W.: J. Chem. Soc. Faraday Trans. 2, 84, 569, 1988. Lesclaux, R. and Caralp, F.: Int. J. Chem. Kinet., 16, 1117, 1984. Lesclaux, R., Caralp, F. and Dognon, A. M.: Geophys. Res. Lett., 13, 933, 1986. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4378 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.206 CFCl O NO + M→ CFCl O + NO + M 2 2 2 2 2 2 ◦ −1 1H = 107 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data −1 k /s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −2 1.0× 10 exp(-10860/T ) [N ] 260-300 Koppenkastrop ¨ and Zabel, 1991 (a) Comments (a) Reaction studied in a temperature-controlled 420 liter reaction chamber, monitoring the reactant by long-path IR absorp- tion. Measurements at 11, 82, and 800 mbar pressure. Falloff extrapolations using F = 0.28 and k = 6.6 × 10 c ∞ −1 exp(-12240/T ) s . Preferred Values −2 −1 k = 1.0× 10 exp(-10860/T ) [N ] s over the temperature range 260–300 K. 0 2 Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The only available measurements are preferred with the employed F = 0.28. The data are consistent with related reactions. High-pressure rate coefﬁcients Rate coefﬁcient data −1 k /s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients 4.0× 10 exp(-12300/T ) 274-305 Simonaitis et al., 1979 (a) 6.0× 10 exp(-12240/T ) 260-300 Koppenkastrop ¨ and Zabel, 1991 (b) Comments (a) Steady-state photolysis of Cl -CHFCl -O -NO-NO mixtures at 1 bar. Simulation of the mechanism depending on the 2 2 2 2 extent of various Cl-consuming reactions. k was assumed to be close to k . (b) See comment (a) for k . Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4379 Preferred Values 16 −1 k = 6.6× 10 exp(-12240/T ) s over the temperature range 260-300 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The agreement between the results from Simonatis et al. (1979) and Koppenkastrop ¨ and Zabel (1991) at 298 K and 1 bar within a factor of 1.5 appears satisfactory. The data from Koppenkastrop and Zabel (1991) are preferred. References Koppenkastrop, ¨ D. and Zabel, F.: Int. J. Chem. Kinet., 23, 1, 1991. Simonaitis, R., Glavas, S. and Heicklen, J.: Geophys. Res. Lett., 6, 385, 1979. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4380 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.207 CCl O + NO + M→ CCl O NO + M 3 2 2 3 2 2 ◦ −1 1H = -105.6 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k / cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −29 −6.0 (9.2± 3)× 10 (T /298) [O ] 233-373 Caralp et al., 1988 PLP-MS (a) Comments (a) Pulsed laser photolysis-MS study at pressures of 1.3–13 mbar. Falloff extrapolation with F = exp(-T /260), i.e. F = 0.32 c c −12 −0.3 3 −1 −1 at 298 K and k = 1.49× 10 (T /298) cm molecule s . Preferred Values −29 −6.0 3 −1 −1 k = 9.2× 10 (T /298) [N ] cm molecule s over the temperature range 230–380 K. 0 2 Reliability 1 log k =± 0.3 at 298 K. 1 n =± 2. Comments on Preferred Values There is a single experimental study only. However, according to the analysis by Destriau and Troe (1990) it falls in line with related reactions. Equal values for k are assumed for the bath gases O and N . The F value should be used independent of 0 2 2 c the temperature. High-pressure rate coefﬁcients Rate coefﬁcient data 3 −1 −1 k / cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 −0.3 (1.49± 0.8)× 10 (T /298) 233-373 Caralp et al., 1988 PLP-MS (a) Comments (a) See comment (a) for k . Preferred Values −12 −0.7 3 −1 −1 k = 1.5× 10 (T /298) cm molecule s over the temperature range 230-380 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4381 Reliability 1 log k =± 0.3 at 298 K. 1 n =± 0.5 Comments on Preferred Values See Comments on Preferred Values for k . Recommending a temperature-independent F = 0.32 is consistent with changing n 0 c from−0.3 to−0.7 such as preferred for related reactions. References Caralp, F., Lesclaux, R., Rayez, M.-T., Rayez, J.-C. and Forst, W.: J. Chem. Soc. Faraday Trans. 2, 84, 569, 1988. Destriau, M. and Troe, J.: Int. J. Chem. Kinet., 22, 915, 1990. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4382 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.208 CCl O NO + M→ CCl O + NO + M 3 2 2 3 2 2 ◦ −1 1H = 105.6 kJ·mol Low-pressure rate coefﬁcients Rate coefﬁcient data −1 k /s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −3 6.3× 10 exp(-10235/T ) [N ] 260-300 Koppenkastrop ¨ and Zabel, 1991 (a) Comments (a) Thermal decomposition of CCl O NO studied in a temperature-controlled 410 liter reaction chamber. The reactant was 3 2 2 monitored by in situ long-path IR absorption. Pressures of N of 11, 82, and 800 mbar were employed. The data were 16 −1 extrapolated with F = 0.22 and k = 4.8× 10 exp(-11820/T ) s . c ∞ Preferred Values −3 −1 k = 4.3× 10 exp(-10235/T ) [N ] s over the temperature range 260–300 K. 0 2 Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values There is a single study of the falloff curve only. However, it is consistent with data for the reverse reaction from Caralp et al. (1988). Some readjustment will be necessary to make F identical for the forward and reverse reaction, for which F = 0.32 c c was chosen. If F = 0.32 replaces F = 0.22, k for the dissociation decreases by about a factor of 0.7 such as preferred here. c c 0 High-pressure rate coefﬁcients Rate coefﬁcient data −1 k /s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients 1.42× 10 exp(-11500/T ) 274-305 Simonaitis et al., 1979 (a) 0.24 298 6.6× 10 exp(-12240/T ) 260-300 Koppenkastrop ¨ and Zabel, 1991 (b) 0.29 298 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4383 Comments (a) Steady-state photolysis of Cl -CHCl -O -N -NO-NO mixtures at 1 bar. Product formation monitored by IR spec- 2 3 2 2 2 troscopy. Some assumption about the mechanism had to be made. The reaction was assumed to be at the high pressure limit. (b) See comment (a) for k . Preferred Values 16 −1 k = 4.8× 10 exp(-11820/T ) s over the temperature range 260-300 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The two available measurements are in close agreement such that k appears well established. For the falloff curve see Comments on Preferred Values for k . References Koppenkastrop, ¨ D. and Zabel, F.: Int. J. Chem. Kinet., 23, 1, 1991. Simonaitis, R., Glavas, S. and Heicklen, J.: Geophys. Res. Lett., 6, 385, 1979. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4384 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.209 C H O + CF CCl O → CH CHO + CF CCl OH + O (1) 2 5 2 3 2 2 3 3 2 2 → C H O + CF CCl O + O (2) 2 5 3 2 2 Rate coefﬁcient data (k= k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 k = (3.6± 0.5)× 10 298 Hayman et al., 1994 PLP-UVA (a) +9 −13 k = (9 )× 10 298 −5 Comments (a) Laser ﬂash photolysis-UV absorption study of CF CCl -C H -O -N mixtures. Kinetic data were obtained by analyzing 3 3 2 6 2 2 two sets of transient decays on the basis of a mechanism consisting of 13 reactions. Preferred Values −12 3 −1 −1 k = 3.6× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 9× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 log k =± 0.5 at 298 K. Comments on Preferred Values While the above values of the rate coefﬁcients appear reasonable, they have been derived from the analysis of a complex chemical system and require independent veriﬁcation to reduce the recommended error limits. References Hayman, G. D., Jenkin, M. E., Murrells, T. P. and Johnson, C. E.: Atmos. Environ., 28A, 421, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4385 IV.A2.210 CF ClCH O + CF ClCH O → CF ClCH OH + CF ClCHO + O (1) 2 2 2 2 2 2 2 2 2 2 → CF ClCH O + CF ClCH O + O (2) 2 2 2 2 2 Rate coefﬁcient data (k= k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 k = (4.13± 0.58)× 10 298 Wallington and Nielsen, 1991 FP-UVA (a,b) obs Branching Ratios k /k ≈ 1.0 298 Tuazon and Atkinson, 1994 UV-P-FTIR (c) Comments (a) k is based on the measured overall second-order decay of CF ClCH O , deﬁned by -d[CF ClCH O ]/dt = 2k obs 2 2 2 2 2 2 obs [CF ClCH O ] . As described in detail by Lesclaux (1997), HO radicals formed from the subsequent chemistry of 2 2 2 2 CF ClCH O (formed from channel (2)) are expected to lead to secondary removal of CF ClCH O . The true value of k 2 2 2 2 2 is expected to fall in the range k /(1+ α) < k < k where α = k /k. obs obs 2 (b) Pulse radiolysis study of CF ClCH -O -SF mixtures over the pressure range 150–1000 mbar. CF ClCH O radicals 2 3 2 6 2 2 2 −18 2 −1 were monitored by UV absorption with σ = (3.38± 0.68)× 10 cm molecule . 250 nm (c) Photolysis of Cl in the presence of CF ClCH -air mixtures at 987 mbar pressure. In situ monitoring of reactants and 2 2 3 products by FTIR spectroscopy was consistent with formation of CF ClCHO with a yield ca. 100%, once corrections were made for secondary removal. Preferred Values −12 3 −1 −1 k = 2.8× 10 cm molecule s at 298 K. k /k = 1.0 at 298 K. Reliability 1 log k =± 0.4 at 298 K. +0.0 1 (k /k) = at 298 K. −0.2 Comments on Preferred Values The observed formation of CF ClCHO in ca. 100% yield from CF ClCH oxidation in the product study of Tuazon and 2 2 3 Atkinson (1994) is consistent with the reaction proceeding predominantly via the radical forming channel (2), followed by reaction of CF ClCH O with O to form CF ClCHO and HO . This also indicates that secondary removal of CF ClCH O 2 2 2 2 2 2 2 2 by reaction with HO must generate CF ClCHO as the major carbon-containing product, in a similar fashion to the observed 2 2 dominant formation of HC(O)Cl from the reaction of HO with CH ClO (Wallington et al., 1996). 2 2 2 The preferred value of k at 298 K is derived from the k value reported by Wallington and Nielsen (1991). Similar to a obs −12 3 procedure adopted by Lesclaux (1997) for peroxy radicals for which the self reaction rate coefﬁcients are≥ ca. 2× 10 cm −1 −1 molecule s , k is estimated to be k /(1 + 0.5(k /k)), with this approximation assuming that the secondary reaction of HO obs 2 2 with CF ClCH O competes equally with its removal via HO + HO . The reliability range reﬂects that k has been derived by 2 2 2 2 2 this approximate procedure. Conﬁrmatory kinetics and product studies are required. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4386 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Lesclaux, R.: Combination of peroxyl radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z. B.. John Wiley and Sons, 1997. Tuazon, E. C. and Atkinson, R.: Environ. Sci. Technol., 28, 2306, 1994. Wallington, T. J. and Nielsen, O. J.: Int. J. Chem. Kinet., 23, 785, 1991. Wallington, T. J., Hurley, M. D. and Schneider, W. F.: Chem. Phys. Lett., 251, 164, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4387 IV.A2.211 CFCl CH O + CFCl CH O → CFCl CH OH + CFCl CHO + O (1) 2 2 2 2 2 2 2 2 2 2 → CFCl CH O + CFCl CH O + O (2) 2 2 2 2 2 Rate coefﬁcient data (k= k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 k = (4.36± 0.64)× 10 298 Wallington and Nielsen, 1991 PR-UVA (a,b) obs Branching Ratios k /k ≈ 1.0 298 Tuazon and Atkinson, 1994 UV-P-FTIR (c) Comments (a) k is based on the measured overall second-order decay of CFCl CH O , deﬁned by -d[CFCl CH O ]/dt = 2k obs 2 2 2 2 2 2 obs [CFCl CH O ] . As described in detail by Lesclaux (1997), HO radicals formed from the subsequent chemistry of 2 2 2 2 CFCl CH O (formed from channel (2)) are expected to lead to secondary removal of CFCl CH O . The true value of k 2 2 2 2 2 is expected to fall in the range k /(1+ α) < k < k where α = k /k. obs obs 2 (b) Pulse radiolysis study of CFCl CH -O -SF mixtures over the pressure range 152–1013 mbar. CFCl CH O radicals 2 3 2 6 2 2 2 −18 2 −1 were monitored by UV absorption with σ = (3.38± 0.68)× 10 cm molecule . 250 nm (c) Photolysis of Cl in the presence of CFCl CH -air mixtures at 987 mbar pressure. In situ monitoring of reactants and 2 2 3 products by FTIR spectroscopy was consistent with formation of CFCl CHO with a yield ca. 100%, once corrections were made for secondary removal. Preferred Values −12 3 −1 −1 k = 2.9× 10 cm molecule s at 298 K. k /k = 1.0 at 298 K. Reliability 1 log k =± 0.4 at 298 K. +0.0 1 (k /k) = at 298 K. −0.2 Comments on Preferred Values The observed formation of CFCl CHO in ca. 100% yield from CFCl CH oxidation in the product study of Tuazon and 2 2 3 Atkinson (1994) is consistent with the reaction proceeding predominantly via the radical forming channel (2), followed by reaction of CFCl CH O with O to form CFCl CHO and HO . This also indicates that secondary removal of CFCl CH O 2 2 2 2 2 2 2 2 by reaction with HO must generate CFCl CHO as the major carbon-containing product, in a similar fashion to the observed 2 2 dominant formation of HCOCl from the reaction of HO with CH ClO (Wallington et al., 1996). 2 2 2 The preferred value of k at 298 K is derived from the k value reported by Wallington and Nielsen (1991). Similar to a obs −12 3 procedure adopted by Lesclaux (1997) for peroxy radicals for which the self reaction rate coefﬁcients are≥ ca. 2× 10 cm −1 −1 molecule s , k is estimated to be k /(1 + 0.5(k /k)), with this approximation assuming that the secondary reaction of HO obs 2 2 with CFCl CH O competes equally with its removal via HO + HO . The reliability range reﬂects that k has been derived by 2 2 2 2 2 this approximate procedure. Conﬁrmatory kinetics and product studies are required. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4388 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Lesclaux, R.: Combination of peroxyl radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z. B., John Wiley and Sons, 1997. Tuazon, E. C. and Atkinson, R.: Environ. Sci. Technol., 28, 2306, 1994. Wallington, T. J. and Nielsen, O. J.: Int. J. Chem. Kinet., 23, 785, 1991. Wallington, T. J., Hurley, M. D. and Schneider, W. F.: Chem. Phys. Lett., 251, 164, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4389 IV.A2.212 CF CCl O + CF CCl O → CF CCl O + CF CCl O + O 3 2 2 3 2 2 3 2 3 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 k = (3.33± 0.53)× 10 295 Wallington et al., 1994 PR-UVA (a,b) obs −12 (3.6± 0.5)× 10 298 Hayman et al., 1994 LP-UVA (c) Comments (a) k is based on the measured overall second-order decay of CF CCl O , deﬁned by -d[CF CCl O ]/dt = obs 3 2 2 3 2 2 2k [CF CCl O ] . obs 3 2 2 (b) Pulse radiolysis study of CF CHCl -O -SF mixtures over the pressure range of 1013 mbar. CF CCl O radicals were 3 2 2 6 3 2 2 −18 2 −1 monitored by UV absorption with σ = (1.70 ± 0.26) × 10 cm molecule . The derived value of k was deter- 250 nm mined from the measured overall second-order decay of CF CCl O radicals. 3 2 2 (c) CF CCl O radicals were generated by 193 nm laser ﬂash photolysis of CF CCl -CH OH-O -N mixtures and CF CCl - 3 2 2 3 3 3 2 2 3 3 C H -O -N mixtures at a total pressure of 1013 mbar. CF CCl O radicals were monitored by UV absorption in the 2 6 2 2 3 2 2 −18 3 −1 range 230–270nm, with σ = (1.79 ± 0.18) × 10 cm molecule . k determined from global simulation of two 250 nm sets of transient decays observed at 230, 240, 250, 260 and 270 nm using a 15 reaction mechanism. Rate coefﬁcients for the reactions CF CCl O with HO and C H O were determined simultaneously. 3 2 2 2 2 5 2 Preferred Values −12 3 −1 −1 k = 3.5× 10 cm molecule s at 298 K. Reliability 1 log k =± 0.3 at 298 K. Comments on Preferred Values The reported formation of CF C(O)Cl with approximately 100% yield from CF CHCl oxidation in a number of product stud- 3 3 2 ies (Edney et al., 1991; Tuazon and Atkinson, 1993; Hayman et al., 1994) has established that the self-reaction of CF CCl O 3 2 2 proceeds essentially exclusively via formation of CF CCl O radicals, which decompose by elimination of Cl. This is also 3 2 supported by the UV spectral study of CF CCl O by Jemi-Alade et al. (1991), involving ﬂash photolysis-UV absorption of 3 2 2 Cl in the presence of CF CHCl and O . In that study, no decay in the absorption due to CF CCl O was observed over a 40 2 3 2 2 2 2 2 ms time scale, demonstrating near-quantitative regeneration of Cl atoms, and therefore CF CCl O , in the system. 3 2 2 The kinetics studies of Wallington et al. (1994) and Hayman et al. (1994) reported UV absorption spectra for CF CCl O 3 2 2 which are in excellent agreement in both shape and magnitude with that reported by Jemi-Alade et al. (1991). The values of k reported by Wallington et al. (1994) and Hayman et al. (1994) are also in close agreement, even though only the methodology of Hayman et al. (1994) was designed to preclude the regeneration of CF CCl O , and to extract the true value of k. It is noted 3 2 2 that Wallington et al. (1994) made use of concentrations of CF CCl O radicals which were an order of magnitude higher 3 2 2 than those in the experiments of Hayman et al. (1994) (and Jemi-Alade et al. (1991)), such that other secondary reactions of CF CCl O and/or Cl might partially preclude regeneration of CF CCl O , or lead to secondary removal of CF CCl O . The 3 2 3 2 2 3 2 2 agreement with the study of Hayman et al. (1994) is therefore likely to be fortuitous. The preferred value at 298 K is based on the rate coefﬁcient reported by Hayman et al. (1994), with the reliability range reﬂecting the requirement to simulate a comparatively complex system to extract k. Further kinetics studies are required to allow k to be deﬁned more accurately. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4390 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Edney, E. O., Gay, Jr., B. W. and Driscoll, D. J.: J. Atmos. Chem., 12, 105, 1991. Hayman, G. D., Jenkin, M. E., Murrells, T. P. and Johnson, C. E.: Atmos. Environ., 28A, 421, 1994. Jemi-Alade, A. A., Lightfoot, P. D. and Lesclaux, R.: Chem. Phys. Lett., 179, 119, 1991. Tuazon, E. C. and Atkinson, R.: J. Atmos. Chem., 17, 179, 1993. Wallington, T. J., Ellermann, T. and Nielsen, O. J.: Res. Chem. Intermed., 20, 265, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4391 IV.A2.213 CH ClO + CH ClO → CH ClOH + HC(O)Cl + O (1) 2 2 2 2 2 2 → 2CH ClO + O (2) 2 2 Rate coefﬁcient data (k= k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 k = 3.1× 10 exp[(735± 95)/T ] 228-380 Dagaut et al., 1988 FP-UVA (a,b) obs −12 k = (3.78± 0.45)× 10 289 obs −13 1.95× 10 exp[(874± 26)/T ] 251-600 Catoire et al., 1994 FP-UVA (c) −12 (4.2± 0.4)× 10 298 −12 (3.3± 0.7)× 10 298 Biggs et al., 1999 DF-LIF/RF (d) Branching Ratios k /k ≈ 1.0 305 Sanhueza and Heicklen, 1975 UVP-IR (e) k /k ≈ 1.0 298 Niki et al., 1980 UVP-FTIR (f) Comments (a) k is based on the measured overall second-order decay of CH ClO , deﬁned by -d[CH ClO ]/dt = 2k [CH ClO ] . obs 2 2 2 2 obs 2 2 As described in detail by Lesclaux (1997), HO radicals formed from the subsequent chemistry of CH ClO (formed from 2 2 channel (2)) are expected to lead to secondary removal of CH ClO . The true value of k is expected to fall in the range 2 2 k /(1 + α) < k < k , where α = k /k. obs obs 2 (b) Flash photolysis of Cl in the presence of CH Cl-O -N mixtures at total pressures of 33–533 mbar at 298 K and of 133 2 3 2 2 mbar (N ) from 228–380 K. Peroxy radical concentrations were monitored by UV absorption with σ = (3.14± 0.45) 2 250 nm −18 2 −1 × 10 cm molecule . (c) Flash photolysis of Cl in the presence of CH Cl-O -N mixtures at a total pressure of 1000 mbar. Peroxy radical 2 3 2 2 concentrations were monitored by UV absorption in the wavelength range 205 to 290 nm, with σ = (3.40± 0.20)× 250 nm −18 2 −1 10 cm molecule in the temperature range 251 to 393 K (decreasing at higher temperatures). Values of k /σ obs 250 nm are in excellent agreement with those of Dagaut et al. (1988) over the common temperature range. Observed decays in transient absorption were found to be distorted from second order kinetics at wavelengths < 250 nm where HO absorbs signiﬁcantly, allowing k and the rate coefﬁcient for the reaction of HO with CH ClO to be extracted via an iterative 2 2 2 procedure. (d) Experiments performed at pressures in the range 1.3 to 4 mbar. CH ClO radicals were produced by the F + CH Cl 2 2 3 reaction, with subsequent addition of O . CH ClO radicals were monitored by titration to NO following reaction with 2 2 2 2 excess NO, with LIF detection of NO . HO radicals generated from the subsequent chemistry of CH ClO (formed 2 2 2 from channel (2)) were also titrated to NO under the experimental conditions, but were independently measured through detection of simultaneously formed HO, by RF. k values were extracted by numerical simulation of the results, using an 8 reaction scheme. (e) Photolysis of Cl in the presence of CH Cl-O mixtures. In situ monitoring of products by IR showed exclusive formation 2 3 2 of HCl and HC(O)Cl as the initial products. (f) Photolysis of Cl in the presence of CH Cl-air mixtures. In situ monitoring of reactants and products by FTIR spec- 2 3 troscopy showed 90-95% conversion of CH Cl to HC(O)Cl. Tentative observation of CH ClOOH at yields up to ca. 3 2 10%, and H O , is indicative of the occurrence of partial reaction of HO with CH ClO in competition with the HO 2 2 2 2 2 2 self reaction. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4392 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values −12 3 −1 −1 k = 3.5× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 1.9× 10 exp(870/T ) cm molecule s over the temperature range 250-600 K. k /k = 1.0 at 298 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 200 K. +0.0 1 (k /k) = at 298 K. −0.1 Comments on Preferred Values The results of the product studies (Sanhueza and Heicklen, 1975; Niki et al., 1980) are consistent with the radical-forming channel (2) being essentially exclusive for the self-reaction of CH ClO radicals. 2 2 The preferred value of k at 298 K is the average of the results of Catoire et al. (1994) (based on their Arrhenius expression) and Biggs et al. (1999), which allowed extraction of k from full appraisal of the reaction mechanism. The preferred Arrhenius expression for k is based on the E/R value from the comprehensive temperature dependence study of Catoire et al. (1994), combined with a pre-exponential factor adjusted to give the preferred value of k at 298 K. As noted above, the earlier k obs data of Dagaut et al. (1988) are also in excellent agreement with those of Catoire et al. (1994) when both sets of data are analyzed by a simple second-order treatment from results derived at λ= 250 nm, and are therefore also consistent with this recommendation. References Biggs, P., Canosa-Mas, C. E., Percival, C. J., Shallcross, D. E. and Wayne, R. P.: Int. J. Chem. Kinet. 31, 433, 1999. Catoire, V., Lesclaux, R., Lightfoot, P. D. and Rayez, M.-T.: J. Phys. Chem. 98, 2889, 1994. Dagaut, P., Wallington, T. J. and Kurylo, M. J.: Int. J. Chem. Kinet. 20, 815, 1988. Lesclaux, R.: Combination of peroxyl radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z. B., John Wiley and Sons, 1997. Niki, H., Maker, P. D., Savage, C. M. and Breitenbach, L. P.: Int. J. Chem. Kinet. 12, 1001, 1980. Sanhueza, E. and Heicklen, J.: J. Phys. Chem. 79, 7, 1975. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4393 IV.A2.214 CHCl O + CHCl O → CHCl OH + C(O)Cl + O (1) 2 2 2 2 2 2 2 → CHCl O + CHCl O + O (2) 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (1-10)× 10 300 Catoire et al., 1996 FP-UVA (a) −12 (7.0± 1.8)× 10 298 Biggs et al., 1999 DF-LIF (b) Branching Ratios k /k ≥ 0.85 305 Sanhueza and Heicklen, 1975 UVP-IR (c) k /k ≥ 0.88 298 Niki et al., 1980 UVP-FTIR (d) k /k ≥ 0.85 298 Catoire et al., 1996 UVP-FTIR (e) k /k ≥ 0.9 250-325 Catoire et al., 1996 FP-UVA (f) Comments (a) Flash photolysis of CHCl in the presence of CH OH-O -N mixtures at a total pressure of 1000 mbar. Decays in transient 3 3 2 2 absorption signals (with contributions from CHCl O and HO ) were recorded in the wavelength range 220 nm to 250 2 2 2 nm. Approximate value of k derived in conjunction with determination of the rate coefﬁcient for the reaction of CHCl O 2 2 with HO , using a ﬁve reaction mechanism. Authors indicate that best ﬁts were obtained using values of k close to those measured for the self reactions of CH ClO and CCl O (which are almost identical) in the same laboratory (Catoire 2 2 3 2 −13 3 et al., 1994; 1996), and recommend that k is the average these determinations: 2.6 × 10 exp[(800 ± 60)/T ] cm −1 −1 −12 3 −1 −1 molecule s over the temperature range 273 K to 460 K, with k= (3.8± 1.4)× 10 cm molecule s at 298 K. (b) Experiments performed at pressures in the range 1.3 to 4 mbar. CHCl O radicals were produced by the F + CH Cl 2 2 2 2 reaction, with subsequent addition of O . CHCl O radicals were monitored indirectly by titration to NO following 2 2 2 2 reaction with excess NO, with LIF detection of NO . ClO radicals generated by the secondary chemistry were also titrated to NO under the experimental conditions. k values were extracted by numerical simulation of the results, using an 11 reaction scheme to take account possible of secondary reactions. (c) Photolysis of Cl in the presence of CH Cl -O -N mixtures. In situ monitoring of products by IR showed formation of 2 2 2 2 2 HC(O)Cl as the dominant product as part of an efﬁcient chain mechanism. C(O)Cl was observed as a minor product. Listed quantum yield based on the reported quantum yield of 5.9 for HC(O)Cl formation. (d) Photolysis of Cl in the presence of CH Cl -O -N mixtures. In situ monitoring of products by FTIR spectroscopy 2 2 2 2 2 showed formation of HC(O)Cl as the dominant product as part of an efﬁcient chain mechanism. C(O)Cl was observed as a minor product. Listed quantum yield based on the reported quantum yield of 7.5 for HC(O)Cl formation. (e) Photolysis of Cl or F in the presence of CH Cl -O -N mixtures. In situ monitoring of products by FTIR spectroscopy 2 2 2 2 2 2 showed formation of HC(O)Cl and C(O)Cl with yields of ca. 85% and 5% respectively. No other primary products were detected. (f) Flash photolysis of Cl in the presence of CH Cl -O -N mixtures over the temperature range 250 K to 325 K demon- 2 2 2 2 2 strated efﬁcient chain regeneration of CHCl O in the system. 2 2 Preferred Values k /k = 1.0 at 298 K. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4394 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Reliability +0.0 1 (k /k) = at 298 K. −0.15 Comments on Preferred Values The reported dominant chain formation of HC(O)Cl from CH Cl oxidation in a number of product studies (Sanhueza and 2 2 Heicklen, 1975; Niki et al., 1980; Catoire et al., 1996) has established that the self-reaction of CHCl O proceeds almost 2 2 exclusively via formation of CHCl O radicals (channel (2)), which decompose by elimination of Cl. This is also supported by the failure to detect CHCl OH in all the product studies, which would otherwise provide evidence for channel (1). The efﬁcient chain regeneration of CHCl O radicals observed in the Cl -CH Cl -O -N ﬂash photolysis experiments of Catoire 2 2 2 2 2 2 2 et al. (1996) is also consistent with the dominance of channel (2) over a wide temperature range. The reported determinations of k (Catoire et al., 1996; Biggs et al., 1999) are subject to substantial uncertainties, owing to the complexity of the secondary chemistry. Catoire et al. (1996) report only a broad range for k at 300K, based on simulations of a complex system in which competitive removal of CHCl O by reaction with HO was occurring (see note (a) above). 2 2 2 The discharge ﬂow determination of Biggs et al. (1999) was complicated by indirect detection of CHCl O (which also had 2 2 contributions from ClO), and possible secondary chain removal of CHCl O via reactions with Cl and ClO. Consequently, no 2 2 ﬁrm recommendation for k is currently possible, and further kinetics studies are required. References Biggs, P., Canosa-Mas, C. E., Percival, C. J., Shallcross, D. E. and Wayne, R. P.: Int. J. Chem. Kinet. 31, 433, 1999. Catoire, V., Lesclaux, R., Lightfoot, P. D. and Rayez, M.-T.: J. Phys. Chem. 98, 2889, 1994. Catoire, V., Lesclaux, R., Schneider, W. F. and Wallington, T. J.: J. Phys. Chem. 100, 14356 1996. Niki, H., Maker, P. D., Savage, C. M. and Breitenbach, L. P.: Int. J. Chem. Kinet. 12, 1001, 1980. Sanhueza, E. and Heicklen, J.: J. Phys. Chem. 79, 7, 1975. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4395 IV.A2.215 CCl O + CCl O → CCl O + CCl O + O 3 2 3 2 3 3 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 −(3.0±1.0) 1.6× 10 (T /298) 253-333 Danis et al., 1991 FP-UVA (a,b) −13 3.3× 10 exp[(745± 58)/T ] 273-460 Catoire et al., 1996 FP-UVA (a,c) −12 (4.07± 0.54)× 10 298 Comments (a) k is deﬁned by -d[CCl O ]/dt = 2k[CCl O ] . 3 2 3 2 (b) Flash photolysis of Cl in the presence of CHCl -O -N mixtures at 1013 mbar total pressure. k was determined from 2 3 2 2 the formation of C(O)Cl , using UV absorption spectroscopy at 240 nm. Results were consistent with chain formation of C(O)Cl , resulting from thermal decomposition of CCl O to generate C(O)Cl and regenerate Cl. 2 3 2 (c) Flash photolysis of Cl in the presence of CHCl -O -N mixtures at 1013 mbar total pressure. k was determined from 2 3 2 2 time-resolved UV absorption at 230 nm, 240 nm and 250 nm, which was dominated by formation of C(O)Cl as part of an efﬁcient chain mechanism. Results were consistent with a chain length of ca. 100. FTIR product studies of the photolysis of Cl -CHCl -O -N mixtures and F -CHCl -O -N mixtures also demonstrated 100% formation of C(O)Cl . 2 3 2 2 2 3 2 2 2 Preferred Values −12 3 −1 −1 k = 4.0× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 3.3× 10 exp(740/T ) cm molecule s over the temperature range 270-460 K. Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The reported formation of C(O)Cl with 100% yield from CHCl oxidation in a number of product studies (Jayanty et al., 2 3 1975; Ohta and Mizoguchi, 1980; Catoire et al., 1996) has established that the self-reaction of CCl O proceeds exclusively 3 2 via formation of CCl O radicals, which decompose by elimination of Cl. This is also supported by the kinetics study of Catoire et al. (1996), involving ﬂash photolysis-UV absorption of Cl in the presence of CHCl and O . The results demonstrate 2 3 2 essentially quantitative regeneration of Cl atoms in the system, the chain length for conversion of CHCl into C(O)Cl being 3 2 ca. 100. The preferred values are based on the results of Catoire et al. (1996), which supersede those of Danis et al. (1991) (also cited in Russell et al., 1990) performed in the same laboratory. Catoire et al. (1996) demonstrated that the smaller formation rate of C(O)Cl and shorter chain lengths observed in the earlier study (Danis et al., 1991) resulted from traces of ethanol which are invariably present in commercial samples of the reagent CHCl . Ethanol is three orders of magnitude more reactive than CHCl towards Cl, and can therefore scavenge a proportion of Cl atoms when present in trace amounts. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4396 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Catoire, V., Lesclaux, R., Schneider, W. F. and Wallington, T. J.: J. Phys. Chem., 100, 14356, 1996. Danis, F., Caralp, F., Rayez, M.-T. and Lesclaux, R.: J. Phys. Chem., 97, 7300, 1991. Jayanty, R. K. M., Simonaitis, R. and Heicklen, J.: J. Photochem., 4, 203, 1975. Ohta, T. and Mizoguchi, I.: Int. J. Chem. Kinet., 12, 717, 1980. Russell, J. J., Seetula, J. A., Gutman, D., Danis, F., Caralp, F., Lightfoot, P. D., Lesclaux, R., Melius, C. F. and Senkan, S. M.: J. Phys. Chem., 94, 3277, 1990. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4397 IV.A2.216 CH CHClO + CH CHClO → CH CHClOH + CH COCl + O (1) 3 2 3 2 3 3 2 → 2CH CHClO + O (2) 3 2 Rate coefﬁcient data (k= k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (5.2± 1.3)× 10 295 Maricq et al., 1993 (a,b) Branching Ratios k /k = 0.95± 0.05 295 Maricq et al., 1993 (b) Comments (a) k is deﬁned by -d[CH CHClO ]/dt = 2k[CH CHClO ] . 3 2 3 2 (b) Pulsed photolysis of Cl in the presence of C H Cl-O -N mixtures with time-resolved IR spectral photography and 2 2 5 2 2 transient diode laser absorption measurements. The above rate coefﬁcient and branching ratio were obtained from the time-dependence and magnitude of the secondary HCl rise, by computer simulations involving a mechanism of 24 reac- tions. Preferred Values −12 3 −1 −1 k = 5× 10 cm molecule s at 298 K. k /k = 0.95 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.05 at 298 K. Comments on Preferred Values While the data of Maricq et al. (1993) for the room temperature rate coefﬁcient seem reasonable in relation to the values of other related halogen-containing peroxy radicals, they have been obtained from very indirect measurements. Conﬁrmation by independent measurements is required to lower the recommended error limits. References Maricq, M. M., Shi, J., Szente, J. J., Rimai, L. and Kaiser, E. W.: J. Phys. Chem. 97, 9686, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4398 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.217 CH ClCH O + CH ClCH O → CH ClCH OH + CH ClCHO + O (1) 2 2 2 2 2 2 2 2 2 2 → CH ClCH O + CH ClCH O + O (2) 2 2 2 2 2 Rate coefﬁcient data (k= k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 k = 1.1× 10 exp[(1020± 170)/T ] 228-380 Dagaut et al., 1988 FP-UVA (a,b) obs −12 k = (3.57± 0.57)× 10 298 obs −12 k = (6.0± 0.8)× 10 295 Maricq et al., 1993 FP-UVA (a,c) obs −14 k = 4.0× 10 exp[(1376± 60)/T ] 253-345 Chakir et al., 2003 MM-UVA (a,d) obs −14 k = (4.5± 0.4)× 10 obs Branching Ratios k /k = 0.31 295 Wallington et al., 1990 UV-P-FTIR (e) k /k = 0.69 k /k = 0.43 296 Yarwood et al., 1992 UV-P-FTIR (e) k /k = 0.57 Comments (a) k is based on the measured overall second-order decay of CH ClCH O , deﬁned by -d[CH ClCH O ]/dt = obs 2 2 2 2 2 2 2k [CH ClCH O ] . As described in detail by Lesclaux (1997), HO radicals formed from the subsequent chemistry of obs 2 2 2 2 CH ClCH O (formed from channel (2)) are expected to lead to secondary removal of CH ClCH O . The true value of k 2 2 2 2 2 is expected to fall in the range k /(1 + α) < k < k , where α = k /k. obs obs 2 (b) Flash photolysis of Cl in the presence of C H -O -N mixtures over the pressure range 33–533 mbar. CH ClCH O 2 2 4 2 2 2 2 2 −18 2 −1 concentrations measured by UV absorption spectroscopy using σ = (3.64± 0.39)× 10 cm molecule . 250 nm (c) Pulsed photolysis of Cl in the presence of C H -O -N mixtures at 1013 mbar pressure. Kinetics determined from time- 2 2 4 2 2 resolved UV absorption spectra of CH ClCH O and HO . The values of σ (CH ClCH O ) obtained are ca. 13% greater 2 2 2 2 2 2 2 than those reported by Dagaut et al. (1988). (d) Modulated photolysis of Cl in the presence of C H -O -N mixtures over the pressure range 67–267 mbar. k de- 2 2 4 2 2 obs termined from analysis of modulated absorption waveforms in the wavelength range 215–270nm. The UV absorption spectrum of CH ClCH O characterized simultaneously, agrees well with that of Dagaut et al. (1988) at λ ≥ 240 nm, 2 2 2 −18 2 −1 with σ = (3.56± 0.20)× 10 cm molecule . At shorter wavelengths, cross sections are up to 20% greater. 250 nm (e) Steady-state photolysis of Cl -C H -O -N mixtures at total pressures of 933 mbar with FTIR spectroscopic monitoring 2 2 4 2 2 of the removal of C H and the formation of CH ClCHO, CH ClCH OOH, and CH ClCH OH. The listed branching 2 4 2 2 2 2 2 ratios were derived from the yields of CH ClCH OH and CH ClCHO relative to the decay of C H . 2 2 2 2 4 Preferred Values −12 3 −1 −1 k = 3.3× 10 cm molecule s at 298 K. −14 3 −1 −1 k = 4.2× 10 exp(1300/T ) cm molecule s over the temperature range 220-380 K. k /k = 0.37 at 298 K. k /k = 0.63 at 298 K. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4399 Reliability 1 log k =± 0.3 at 298 K. 1 (E/R) =± 500 K. 1 (k /k) = 1 (k /k) =± 0.1 at 298 K. 1 2 Comments on Preferred Values The studies of Wallington et al. (1990) and Yarwood et al. (1992) provide reasonably consistent determinations of k /k and the preferred value at 298 K is the average of these determinations. Chakir et al. (2003) also used steady state concentrations of HO and CH ClCH O , inferred from their modulated photolysis study, to draw conclusions about the temperature dependence 2 2 2 2 of the branching ratio for HO formation, k /k. Using the 298 K values of Wallington et al. (1990) and Yarwood et al. (1992) 2 2 as a reference, they estimated that k /k varies from ca. 0.3 at 253 K to ca. 0.7–0.9 at 345 K. k /k is expected to tend to unity as 2 2 T increases. The preferred values of k were calculated from the reported values of k and k /k using a methodology similar to that obs 2 −12 3 −1 −1 employed by Lesclaux (1997) for peroxy radicals with self reaction rate coefﬁcients≥ ca. 2× 10 cm molecule s at room temperature. k is estimated to be k /(1 + 0.5(k /k)), with this approximation assuming that the secondary reaction of obs 2 HO with CH ClCH O competes equally with its removal via HO + HO . The preferred values are based on the temperature 2 2 2 2 2 2 dependence kinetics results of Dagaut et al. (1988) and Chakir et al. (2003), and the preferred value of k /k at 298 K, with the assumption that k /k increases to≈ 1 at the high end of the studied temperature range, 380 K. The 298 K value of k reported 2 obs by Maricq et al. (1993) is ca. 50% greater than the average of the values of Dagaut et al. (1988) and Chakir et al. (2003), but is encompassed by the uncertainty range in the preferred value. The discrepancy is not fully resolved, but is partially explained by the greater absorption cross-sections for CH ClCH O reported by Maricq et al. (1993). 2 2 2 References Chakir, A., Brion, J., Ganne, J. P. and Daumont, D.: Phys. Chem. Chem. Phys. 5, 2573, 2003. Dagaut, P., Wallington, T. J. and Kurylo, M. J.: Chem. Phys. Lett. 146, 589, 1988. Lesclaux, R.: Combination of peroxyl radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z.B., John Wiley and Sons, 1997. Maricq, M. M., Shi, J., Szente, J. J., Rimai, L. and Kaiser, E. W.: J. Phys. Chem. 97, 9686, 1993. Wallington, T. J., Andino, J. M. and Japar, S. M.: Chem. Phys. Lett. 165, 189, 1990. Yarwood, G., Peng, N. and Niki, H.: Int. J. Chem. Kinet. 24, 369, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4400 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.218 O + C HCl → products 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −20 < 3× 10 296 Atkinson et al., 1982 S-CL Preferred Values −20 3 −1 −1 k < 5× 10 cm molecule s at 298 K. Comments on Preferred Values The upper limit to the preferred value is taken from the data of Atkinson et al. (1982), with the upper limit being increased by a factor of∼2 to take into account additional uncertainties in the study of Atkinson et al. (1982). This upper limit is consistent with the reported data for the reactions of O with the chloroethenes (Atkinson and Carter, 1984), which show that Cl atom substitution markedly decreases the rate coefﬁcients at room temperature, relative to that for ethene. References Atkinson, R. and Carter, W. P. L.: Chem. Rev., 84, 437, 1984. Atkinson, R., Aschmann, S. M., Fitz, D. R., Winer, A. M. and Pitts, J. N. Jr.: Int. J. Chem. Kinet., 14, 13, 1982. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4401 IV.A2.219 O + C Cl → products 3 2 4 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −23 < 2× 10 297 Mathias et al., 1974 (a) 17 −3 (a) From experiments carried out at initial O and tetrachloroethene concentrations of≥ 10 molecule cm in the presence of excess O , using an assumed mechanism and monitoring the formation rate of C(O)Cl . From the data given in Mathias 2 2 −23 3 −1 −1 et al. (1974), a more conservative upper limit of k < 8 × 10 cm molecule s can be derived by assuming that only one C(O)Cl molecule is formed per tetrachloroethene reacted. Preferred Values −21 3 −1 −1 k < 10 cm molecule s at 298 K. Comments on Preferred Values The upper limit to the preferred value is derived from the very limited amount of data reported by Mathias et al. (1974), with the upper limit to the rate coefﬁcient being increased by a factor of 50 over that reported. This upper limit to the rate coefﬁcient for tetrachloroethene is consistent with the kinetic data for the other chloroethenes (Atkinson and Carter, 1984), which show that Cl atom substitution markedly decreases the reactivity of the chloroethenes towards O , compared to that for ethene. References Atkinson, R. and Carter, W. P. L.: Chem. Rev., 84, 437, 1984. Mathias, E., Sanhueza, E., Hisatsune, I. C. and Heicklen, J.: Can. J. Chem., 52, 3852, 1974. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4402 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.220 CH Cl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CH Cl + hν → CH + Cl 349 343 3 3 Preferred Values Absorption cross-sections for CH Cl at 295 K and 210 K 20 2 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 295 K 210 K 174 111 198 2.66 2.43 176 93.8 200 1.76 1.51 178 76.6 202 1.13 0.93 180 60.7 204 0.750 0.573 182 46.7 206 0.483 0.345 184 35.0 208 0.318 0.212 186 25.5 210 0.206 0.130 188 18.2 212 0.132 0.080 190 12.7 214 0.086 0.047 192 8.72 216 0.055 0.027 194 5.88 196 4.01 No temperature dependence at λ <198 nm. Comments on Preferred Values The preferred values of the absorption cross-sections at 295 K and at 210 K are those reported by Simon et al. (1988). This latter publication reports the results of the most comprehensive study of the temperature dependence. These values are in very good agreement with the room temperature values reported by Robbins (1976) and are in reasonable agreement with the results of Hubrich et al. (1977) who also made low temperature measurements. In the wavelength region 180–216 nm, photolysis occurs with unit quantum efﬁciency by breaking of the C-Cl bond to yield CH + Cl. Photochemistry at shorter wavelengths is discussed by Shold and Rebbert (1978). A H-atom product channel has now been observed using product translational energy studies (Amaral et al., 2001). References Amaral, G., Xu, K. and Zhang, J.: J. Phys. Chem. A 105, 1115, 2001. Hubrich, C., Zetzsch, C. and Stuhl, F.: Ber. Bunsenges. Phys. Chem. 81, 437, 1977. Robbins, D. E.: Geophys. Res. Lett. 3, 213, 1976; erratum op. cit. 3, 757, 1976. Shold, D. M. and Rebbert, R. E.: J. Photochem. 9, 499, 1978. Simon, P. C., Gillotay, D., Vanlaethem-Meuree, N. and Wisemberg, J.: J. Atmos. Chem. 7, 107, 1988. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4403 IV.A2.221 CH OCl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CH OCl + hν → CH O + Cl (1) 202.9 589 3 3 → CH + ClO (2) 312.4 383 → CH OCl + H (3) 417.4 287 Absorption cross-sections for CH Cl at 295 K and 210 K Wavelength/nm Reference Comments 200-460 Crowley et al., 1994 (a) 230-394 Jungkamp et al., 1995 (b) Quantum yield data (φ = φ + φ ) 1 2 Measurement Wavelength region/nm Reference Comments φ = 0.95± 0.05 308 Schindler et al., 1997 (c) φ =1 248 Krisch et al., 2004 (d) Comments (a) Monochromator/diode array set up with spectral resolution of 0.4 nm. The spectrum measured at 295 K showed no dependence on resolution between 0.3 and 1.2 nm. Correction applied for small Cl impurities which were quantiﬁed by MS. (b) Monochromator/double diode array set up (temperature and resolution not quoted). Impurities (CH OH and Cl ) quanti- 3 2 ﬁed by MS. (c) Pulsed laser photolysis (excimer at 308 nm, dye laser at 235 nm) with REMPI-TOF mass spectrometric detection of Cl 2 2 photofragments in both P and P states. The overall quantum yield of Cl atom generation at 308 nm was measured 1/2 3/2 2 2 relative to Cl . The ratio of Cl ( P ) / Cl ( P ) was found to be 0.31± 0.02 at 308 nm and 1.45± 0.05 at 235 nm. 2 1/2 3/2 (d) Crossed laser-molecular beam scattering experiment with detection of photofragments by VUV photoionisation-TOFMS + + (Cl detected as Cl and CH O as CHO ). No other photofragments were observed. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4404 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values Absorption cross-sections for CH OCl at 295 K 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 200 6.61 340 0.908 210 5.41 350 0.649 220 10.0 360 0.441 230 16.1 370 0.296 240 16.6 380 0.203 250 11.5 390 0.144 260 6.00 400 0.108 270 2.75 410 0.082 280 1.56 420 0.064 290 1.35 430 0.048 300 1.44 440 0.037 310 1.49 450 0.027 320 1.39 460 0.020 330 1.18 Quantum yields φ = 1.0 throughout the absorption spectrum Comments on Preferred Values There is very good agreement between the cross sections presented in both studies for λ > 260 nm, (Crowley et al., 1994; Jungkamp et al., 1995) though some differences are observed at the short wavelength end of the spectra. The data of Crowley et al. (1994), which cover a larger wavelength range and extend further into the actinic region are preferred. The preferred overall quantum yield of 1.0 is based on the work of Schindler et al. (1997), which is consistent with the observations of Krisch et al. (2004) and with quantum yields measured for other hypohalites such as HOCl. References Crowley, J. N., Helleis, F., Muller ¨ , R., Moortgat, G. K. and Crutzen, P. J.: J. Geophys. Res. 99, 20683, 1994. Jungkamp, T. P. W., Kirchner, U., Schmidt, M. and Schindler, R. N.: J. Photochem. Photobiol. A 91, 1, 1995. Krisch, M. J., McCunn, L. R., Takematsu, K., Butler, L. J., Blas, F. R. and Shu, J.: J. Phys. Chem. A 108, 1650, 2004. Schindler, R. N., Liesner, M., Schmidt, S., Kirchner, U. and Benter, Th.: J. Photochem. Photobiol. A 107, 9, 1997. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4405 IV.A2.222 CHF Cl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CHF Cl + hν → CHF + Cl (1) 327 327 2 2 → CClF + H (2) 423 283 → CF + HCl (3) 207 287 Absorption cross-sections for CHF Cl at 298 K and 210 K 20 2 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 298 K 298 K 210 K 174 5.72 188 0.372 0.372 176 4.04 190 0.245 0.242 178 2.76 192 0.156 0.148 180 1.91 194 0.103 0.093 182 1.28 196 0.072 0.062 184 0.842 198 0.048 0.039 186 0.576 200 0.032 0.0159 202 0.022 0.0159 204 0.014 0.0096 No temperature dependence at λ < 188 nm. Quantum yields for CHF Cl photolysis φ(1) = 0.84; φ(2) = 0.16 at 193 nm. Comments on Preferred Values The preferred values of the absorption cross-sections at 298 K are those reported by Simon et al. (1988). In the same study (Simon et al., 1988) the temperature dependence down to 210 K has been reported, with the values at the shorter wavelengths being temperature-independent within the precision of the measurements. The values at longer wavelengths show a decrease as the temperature is lowered (Simon et al., 1988). These results are in reasonable agreement with those of earlier studies cited in NASA, 1997. Melchior et al. (1996) studied the photodissociation of CHF Cl at 193 nm using TOF-MS combined with 2+1 REMPI to detect products. Photolysis by 2 channels, C-Cl and C-H bond rupture, was observed; HCl elimination was not found. C-Cl rupture is the main channel. The minor channel yield was φ /φ = 0.16 ± 0.05. This work forms the basis of H total the recommended values at 193 nm. The quantum yields are likely to be wavelength dependent with φ(1) increasing towards 1.0 at the absorption threshold near 205 nm. References Melchior, A., Knupfer, P., Bar, I., Rosenwaks, S., Laurent, T., Volpp, H.-R. and Wolfrum, J.: J. Phys. Chem. 100, 13375, NASA Evaluation: No. 12, 1997 (see references in Introduction). Simon, P. C., Gillotay, D., Vanlaethem-Meuree, N. and Wisemberg, J.: J. Atmos. Chem. 7, 107, 1988. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4406 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.223 CF Cl + hν → products 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF Cl + hν → CF Cl + Cl (1) 346 346 2 2 2 → CF + 2Cl (2) 542 221 Absorption cross-sections for CF Cl at 295 K and 210 K 2 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 174 162 200 8.89 5.11 176 181 202 5.51 2.97 178 187 204 3.44 1.69 180 179 206 2.09 0.99 182 160 208 1.27 0.56 184 134 210 0.76 0.32 186 107 212 0.45 0.18 188 82.8 79.3 214 0.27 0.10 190 63.2 52.9 216 0.16 0.058 192 45.5 35.8 218 0.10 0.033 194 31.5 22.8 220 0.060 0.018 196 21.1 14.4 222 0.036 0.010 198 13.9 8.8 224 0.022 0.006 226 0.013 0.003 No temperature dependence at λ≤ 186 nm. Quantum yields for CF Cl photolysis at 298K 2 2 φ(1) = 1 over the range 190–225 nm. Comments on Preferred Values The preferred values of the absorption cross-sections at 295 K and at 210 K are those reported by Simon et al. (1988). This publication reports the results of the most comprehensive study of the temperature dependence (Simon et al., 1988). The values at room temperature are in good agreement with those recommended in our previous evaluation, CODATA, 1980, where a detailed discussion of earlier work can be found. They also agree with the recommendations of NASA (1997) which include an expression for the temperature dependent cross-sections applicable over the range 190–210 nm: −4 σ = σ (218)exp{4.1×10 (λ - 184.9)(T -298)} [λ in nm; T in K]. More recently the absorption cross-sections of CF Cl at 298 K have been measured over the range 225< λ <110 nm using 2 2 synchrotron radiation (Limao Vieira et al., 2002). The results agree well with those recommended by IUPAC in the overlapping wavelength range. Baum and Huber (1993) studied laser photodissociation of CF Cl at 193 nm, with photoproducts investigated by TOF- 2 2 MS. Results show exclusive dissociation to CF Cl + Cl, with the CF Cl fragment containing insufﬁcient energy for prompt 2 2 dissociation to produce a second Cl atom. This is contrary to the earlier suggestion by Rebbert and Ausloos (1975) that formation of 2 Cl atoms occurred with increasing tendency at wavelengths < 230 nm. For the purposes of atmospheric photolysis a value of φ(1) = 1 is recommended. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4407 References Baum, G. and Huber, R. J.: Chem. Phys. Lett. 203, 261, 1993. CODATA, 1980 (see references in Introduction). Limao Vieira, P., Eden, S., Kendall, P. A., Mason, N. J. and Hoffman, S. V., Chem. Phys. Lett., 364, 535, 2002). NASA: Evaluation No. 12, 1997 (see references in Introduction). Rebbert, R. E. and Ausloos, P. J.: J. Photochem. 4, 419, 1975. Simon, P. C., Gillotay, D., Vanlaethem-Meuree, N. and Wisemberg, J.: J. Atmos. Chem. 7, 107, 1988. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4408 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.224 CFCl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CFCl + hν → CFCl + Cl (1) 317 377 3 2 → CFCl + 2Cl (2) 558 214 Absorption cross-sections for CFCl at 295 K and 210 K 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 174 313 210 14.8 9.9 176 324 212 10.5 6.63 178 323 214 7.56 4.31 180 314 216 5.38 2.78 182 296 218 3.79 1.77 184 272 220 2.64 1.13 186 243 230 222 1.82 0.71 188 213 202 224 1.24 0.45 190 179 170 226 0.84 0.29 192 154 141 228 0.56 0.19 194 124 115 230 0.37 0.12 196 99.1 90.5 235 0.126 198 78.0 71.8 240 0.046 200 64.5 55.8 245 0.017 202 50.0 42.0 250 0.0066 204 37.4 30.0 255 0.0034 206 28.0 21.6 260 0.0015 208 19.7 14.9 No temperature dependence at λ≤ 184 nm. Quantum yields for CFCl photolysis at 298K φ(1) = 1 at λ > 180 nm. Comments on Preferred Values The preferred values of the absorption cross-sections for 174–250 nm at 295 K and 210 K are the values reported by Simon et al. (1988). This publication reports the results of the most comprehensive study of the temperature dependence (Simon et al., 1988). For λ > 230 nm, the absorption cross-section values are those reported by Hubrich and Stuhl (1980). The values are in good agreement with those recommended in our previous evaluation, CODATA, 1982, where a detailed discussion of earlier work can be found. They also agree with the recommendations of NASA (1997) which include an expression for the temperature dependent cross-sections applicable over the range 190–210 nm: −4 σ = σ (218)exp{4.1× 10 (λ-184.9)(T -298)} [λ in nm; T in K]. Felder and Demuth (1993) studied laser photodissociation of CFCl at 193 nm using TOF-MS to investigate the nature and energetics of the photofragments. At this wavelength dissociation occurs exclusively to yield CFCl + Cl products. This result is in conﬂict with the earlier conclusions of Rebbert and Ausloos (1975) that φ(2) increases from 0.06 at 220 nm to 0.43 at 170 nm. This result from indirect experiments must now be considered dubious. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4409 References CODATA, Supplement I, 1982 (see references in Introduction). Felder, P. and Dermuth, C.: Chem. Phys. Lett. 208, 21, 1993. Hubrich, C. and Stuhl, F.: J. Photochem. 12, 93, 1980. NASA: Evaluation No. 12, 1997 (see references in Introduction). Rebbert, R. E. and Ausloos, P. J.: J. Photochem. 4, 419, 1975. Simon, P. C., Gillotay, D., Vanlaethem-Meuree, N. and Wisemberg, J.: J. Atmos. Chem. 7, 107, 1988. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4410 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.225 CCl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CCl + hν → CCl + Cl (1) 288 415 4 3 → CCl + 2Cl (2) 577 207 Preferred Values Absorption cross-sections for CCl at 295 K and 210 K 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 174 990 220 17.5 12.5 176 1010 222 13.6 9.0 178 975 224 10.2 6.4 180 720 226 7.6 4.4 182 590 228 5.6 3.16 184 440 230 4.28 2.27 186 310 232 3.04 1.52 188 198 234 2.20 1.05 190 147 236 1.60 0.72 192 99.2 238 1.16 0.50 194 76.7 240 0.830 0.234 196 69.5 242 0.590 0.234 198 68.0 244 0.413 0.158 200 66.0 246 0.290 0.108 202 63.8 248 0.210 0.076 204 61.0 60.1 250 0.148 0.053 206 57.0 54.4 255 0.066 208 52.5 48.3 260 0.025 210 46.9 41.5 265 0.013 212 41.0 34.8 270 0.006 214 34.5 27.9 275 0.002 216 27.8 21.7 218 22.1 16.3 No temperature dependence at λ < 204 nm. Quantum yields for CCl photolysis at 298K φ(1) = 1 over wavelength range 174–275 nm. Comments on Preferred Values The preferred values of the absorption cross-sections for 174–230 nm at 295 K and 210 K are the values reported by Simon et al. (1988). This recent publication reports the results of the most comprehensive study of the temperature dependence Simon et al. (1988). For λ > 230 nm, the absorption cross-section values are those reported by Hubrich and Stuhl (1980). The values at room temperature are in good agreement with those recommended in our previous evaluation, CODATA, 1982, where a Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4411 detailed discussion of earlier work can be found. Photodissociation via C-Cl bond ﬁssion expected to occur with unit quantum yield. There is also evidence for direct release of a second Cl atom (channel 2) at λ < 220 nm. The earlier results of Rebbert and Ausloos (1976/77) are now supported by pulsed laser photolysis experiments at 193 nm and 135 nm which give φ(Cl) = 1.5± 0.1 and 1.9± 0.1 respectively at these wavelengths (Hanf et al., 2003). References CODATA, Supplement I, 1982 (see references in Introduction). Hanf, A., Lauter ¨ , A. and Volpp, H-R.: Chem. Phys. Lett., 368, 445, 2003. Hubrich, C. and Stuhl, F.: J. Photochem. 12, 93, 1980. Rebbert, R. E. and Ausloos, P. J.: J. Photochem. 6, 265, 1976/77. Simon, P. C., Gillotay, D., Vanlaethem-Meuree, N. and Wisemberg, J.: J. Atmos. Chem. 7, 107, 1988. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4412 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.226 CH CF Cl + hν → products 3 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CH CF Cl + hν → CH CF + Cl 335 (est) 360 3 2 3 2 → CH CF Cl + H 400 (est) 300 2 2 Preferred Values Absorption cross-sections for CH CF Cl at 298 K and 220 K 3 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 298 K 220 K 298 K 220 K 190 1.01 0.75 210 0.017 0.010 192 0.69 0.51 212 0.010 0.006 194 0.49 0.34 214 0.007 0.003 196 0.33 0.22 216 0.004 0.002 198 0.22 0.15 218 0.003 0.001 200 0.14 0.091 220 0.002 0.0007 202 0.09 0.057 222 0.0009 0.0004 204 0.061 0.037 224 0.0005 0.0002 206 0.039 0.024 226 0.0003 0.0001 208 0.026 0.015 228 0.0002 0.0001 Comments on Preferred Values The preferred values of the absorption cross-sections at 298 K are the mean of the values reported by Gillotay and Simon (1991), Orlando et al. (1991) and (for 190–210 nm) Nayak et al. (1996). The agreement between these studies over the wavelength range of preferred values is good. The results of Hubrich and Stuhl (1980) are in reasonable agreement. The temperature dependence down to about 220 K has been reported by Gillotay and Simon (1991), Orlando et al. (1991) and Nayak et al. (1996). The preferred values at 220 K for the wavelength range 190 nm to 210 nm are the mean of the values reported by Gillotay and Simon (1991), Orlando et al. (1991) and Nayak et al. (1996). Because Nayak et al. (1996) did not report values for λ > 210 nm at their lowest temperature of 223 K, and the values of Orlando et al. (1991) at wavelengths greater than approximately 210 nm have been questioned (Gillotay and Simon, 1991; Nayak et al., 1996), the preferred values at 220 K and λ > 210 nm are the values reported by Gillotay and Simon (1991). Photolysis is expected to occur with unit quantum efﬁciency. At 193 nm Melchior et al. (1997) have shown that C-Cl bond ﬁssion to give CH CF + Cl is the main 3 2 channel, but that C-H bond cleavage also occurs with a branching ratio of about 40%. References Gillotay, D. and Simon, P. C.: J. Atmos. Chem. 12, 269, 1991. Hubrich, C. and Stuhl, F.: J. Photochem. 12, 93, 1980. Melchior, A., Bar, I. and Rosenwaks, S.: J. Chem. Phys. 107, 8476, 1997. Nayak, A.K., Buckley, T. J., Kurylo, M. J. and Fahr, A.: J. Geophys. Res. 101, 9055, 1996. Orlando, J. J., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: J. Geophys. Res. 96, 5013, 1991. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4413 IV.A2.227 CH CFCl + hν → products 3 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CH CFCl + hν → CH CFCl + Cl 335 (est) 360 3 2 3 → CH CFCl + H 400 (est) 300 2 2 Preferred Values Absorption cross-sections for CH CFCl at 298 K and 210 K 3 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 298 K 210 K 298 K 210 K 190 83.8 80.1 210 2.1 1.6 192 64.1 59.5 212 1.4 1.0 194 47.4 42.8 214 0.88 0.65 196 34.0 30.0 216 0.57 0.41 198 23.8 20.6 218 0.37 0.26 200 16.4 13.8 220 0.24 0.16 202 11.1 9.2 222 0.16 0.10 204 7.4 6.0 224 0.10 0.06 206 4.9 3.9 226 0.07 0.04 208 3.2 2.5 228 0.04 0.03 Comments on Preferred Values The preferred values of the absorption cross sections at 298 K are the values reported by Fahr et al. (1993). In this study (Fahr et al., 1993), measurements were made in the gas phase (190–260 nm) and the liquid phase (230–260 nm) at 298 K. Correction factors were used to convert these liquid-phase values into accurate gas-phase values at the long wavelengths. Results reported in this study (Fahr et al., 1993) are in very good agreement with those reported by Gillotay and Simon (1991). The results of Talukdar et al. (1991) are lower at shorter wavelengths and higher at longer wavelengths. Gillotay and Simon (1991) and Talukdar et al. (1991) report the temperature dependence down to 210 K. The low temperature values of Gillotay and Simon (1991) are preferred, and their 210 K values are given in the table. Photolysis is expected to occurwith unit quantum efﬁciency. At 193 nm Melchior et al. (1997) have shown that C-Cl bond ﬁssion to give CH CFCl + Cl is the main channel, but that C-H bond cleavage also occurs with a branching ratio of about 15%. H atom formation is also observed at 205-209 nm using the photofragment velocity map imaging technique (Mashino et al., 2005). References Fahr, A., Braun, W. and Kurylo, M. J.: J. Geophys. Res. 98, 20467, 1993. Gillotay, D. and Simon, P. C.: J. Atmos. Chem. 12, 269, 1991. Mashino, M., Yamada, H., Sugita, A. and Kawasaki, M.: J. Photochem. Photobiol. A: Chem., 176, 78, 2005. Melchior, A., Bar, I. and Rosenwaks, S.: J. Chem. Phys. 107, 8476, 1997. Talukdar, R., Mellouki, A., Gierczak, T., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: J. Phys. Chem. 95, 5815, www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4414 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.228 CH CCl + hν → products 3 3 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CH CCl + hν → CH CCl + Cl 335 (est) 360 3 3 3 2 Preferred Values Absorption cross-sections for CH CCl at 295 K and 210 K 3 3 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 182 315 a 210 24.0 19.8 184 280 a 212 16.8 13.2 186 250 a 214 12.0 8.8 188 220 a 216 8.6 6.1 190 192 a 218 6.0 4.2 192 163 a 220 4.1 2.9 194 140 a 222 2.9 1.2 196 118 a 224 2.0 1.2 198 99 a 226 1.5 0.76 200 81 a 228 1.0 0.51 202 66 64 230 0.70 0.33 204 52 49 232 0.49 0.18 206 40 36 234 0.33 0.11 208 31 26 236 0.23 0.064 238 0.15 0.036 240 0.10 0.024 (a) No temperature dependence observed. Comments on Preferred Values The preferred values of the absorption cross-sections at 298 K and at 210 K are the values reported by Vanlaethem-Meuree et al. (1979), who determined absorption cross-section values at 295 K, 270 K, 250 K, 230 K and 210 K for the wavelength range 180–240 nm. These values (Vanlaethem-Meuree et al., 1979) are preferred over the substantially higher values reported by Hubrich and Stuhl (1980), in which study a correction was required for the presence of the UV-absorbing stabilizer 1,4-dioxane. In a recent study, Nayak et al. (1995) reported measurements in the gas phase (160–240 nm) and the liquid phase (235–260 nm) over the temperature range 220–330 K. A wavelength shift procedure was used to convert the liquid-phase values into effective gas-phase values at the long wavelengths. The reported room temperature values of Nayak et al. (1995) are in good agreement (within 15%) with those of Vanlaethem-Meuree et al. (1979) in the range 210–240 nm, whereas in the 180–210 nm range they are 15% to 30% higher. Low temperature results are in relatively good agreement up to 230 nm. Photolysis is expected to occur with unit quantum efﬁciency by breaking of the C-Cl bond to yield CH CCl + Cl. 3 2 References Hubrich, C. and Stuhl, F.: J. Photochem. 12, 93, 1980. Nayak, A. K., Kurylo, M. J. and Fahr, A.: J. Geophys. Res. 100, 11185, 1995. Vanlaethem-Meuree, N., Wisemberg, J. and Simon, P. C.: Geophys. Res. Lett. 6, 451, 1979. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4415 IV.A2.229 CF CHFCl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF CHFCl + hν → CF CHF + Cl 335 (est) 360 3 3 Preferred Values Absorption cross-sections for CF CHFCl at 298 K and 210 K 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 298 K 210 K 298 K 210 K 190 0.77 0.62 210 0.018 0.010 192 0.55 0.42 212 0.012 0.006 194 0.39 0.29 214 0.008 0.004 196 0.27 0.19 216 0.006 0.003 198 0.18 0.13 218 0.004 0.002 200 0.13 0.084 220 0.003 0.0011 202 0.086 0.055 222 0.002 0.0007 204 0.060 0.036 224 0.002 0.0005 206 0.040 0.023 226 0.001 0.0003 208 0.027 0.015 228 0.001 0.0002 Comments on Preferred Values The preferred values of the absorption cross-sections at 298 K are the averages of the values reported by Orlando et al. (1991) and Gillotay and Simon (1991), which are in good agreement. Both studies investigated the temperature dependence down to about 210 K. The temperature dependences of Orlando et al. (1991) are greater for shorter wavelengths (< 200 nm) and less for the longer wavelengths than those reported by Gillotay and Simon (1991). The low temperature values of Gillotay and Simon (1991) are preferred, and their 210 K values are given in the table. Photolysis is expected to occur with unit quantum efﬁciency by breaking of the C-Cl bond to yield CF CHF + Cl. References Gillotay, D. and Simon, P. C.: J. Atmos. Chem. 13, 289, 1991. Orlando, J. J., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: J. Geophys. Res. 96, 5013, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4416 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.230 CF CHCl + hν → products 3 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF CHCl + hν → CF CHCl + Cl 335 (est) 360 3 2 3 Preferred Values Absorption cross-sections for CF CHCl at 298 K and 220 K 3 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 298 K 220 K 298 K 220 K 190 61.5 54.3 210 1.8 1.2 192 46.2 39.7 212 1.3 0.82 194 33.9 28.1 214 0.84 0.55 196 24.1 19.2 216 0.57 0.38 198 17.2 13.4 218 0.38 0.27 200 12.0 9.1 220 0.26 0.18 202 8.3 6.1 222 0.18 0.13 204 5.7 4.1 224 0.12 0.09 206 3.9 2.7 226 0.09 0.06 208 2.7 1.8 228 0.06 0.04 Comments on Preferred Values The preferred values of the absorption cross-sections at 298 K are the mean of the values reported by Gillotay and Simon (1991), Orlando et al. (1991) and Nayak et al. (1996). The agreement between these studies over the wavelength range of preferred values is very good. The temperature dependence down to about 220 K has been reported by Gillotay and Simon (1991), Orlando et al. (1991) and Nayak et al. (1996). The preferred values at 220 K for the wavelength range 190 nm to 220 nm are the mean of the values reported by Gillotay and Simon (1991), Orlando et al. (1991) and Nayak et al. (1996). Because Nayak et al. (1996) did not report values for λ > 220 nm at their lowest temperature of 223 K, and the values of Orlando et al. (1991) at wavelengths greater than approximately 220 nm have been questioned (Gillotay and Simon, 1991; Nayak et al., 1996), the preferred values at 220 K and λ > 220 nm are the values reported by Gillotay and Simon (1991). Photolysis is expected to occur with unit quantum efﬁciency by breaking of the C-Cl bond to yield CF CHCl + Cl. References Gillotay, D. and Simon, P. C.: J. Atmos. Chem. 12, 269, 1991. Nayak, A. K., Buckley, T. J., Kurylo, M. J. and Fahr, N.: J. Geophys. Res. 101, 9055, 1996. Orlando, J. J., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: J. Geophys. Res. 96, 5013, 1991. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4417 IV.A2.231 CF ClCFCl + hν → products 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF ClCFCl + hν → CF ClCFCl + Cl (1) 346 (est) 346 2 2 2 → CFCl CF + Cl (2) 346 (est) 346 2 2 Preferred Values Absorption cross-sections for CF ClCFCl at 295 K and 210 K 2 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 184 118 a 210 1.80 1.12 186 104 a 212 1.15 0.696 188 83.5 a 214 0.760 0.452 190 64.5 a 216 0.505 0.298 192 48.8 a 218 0.318 0.184 194 36.0 a 220 0.220 0.125 196 26.0 24.3 222 0.145 0.081 198 18.3 15.9 224 0.095 0.053 200 12.5 10.1 226 0.063 0.034 202 8.60 6.54 228 0.041 0.022 204 5.80 4.09 230 0.027 0.014 206 4.00 2.66 208 2.65 1.68 (a) No temperature dependence observed. Comments on Preferred Values The preferred values of the absorption cross-sections are those reported by Simon et al. (1988). They are in good agreement with the room temperature results of Chou et al. (1978) and Hubrich and Stuhl (1980), who also made low temperature measurements. Photolysis is expected to occur with unit quantum efﬁciency by breaking of the C-Cl bond to yield CF ClCFCl + Cl or CFCl CF + Cl. 2 2 References Chou, C. C., Milstein, R. J., Smith, W. S., Vera Ruiz, H., Molina, M. J. and Rowland, F. S.: J. Phys. Chem. 82, 1, 1978. Hubrich, C. and Stuhl, F.: J. Photochem. 12, 93, 1980. Simon, P. C., Gillotay, D., Vanlaethem-Meuree, N. and Wisemberg, J.: Ann. Geophysicae 6, 239, 1988. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4418 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.232 CF ClCF Cl + hν → products 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF ClCF Cl + hν → CF ClCF + Cl 346 (est) 346 2 2 2 2 Preferred Values Absorption cross-sections for CF ClCF Cl at 295 K and 210 K 2 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 172 69 a 200 0.80 0.55 174 55 a 202 0.54 0.34 176 43 a 204 0.37 0.22 178 34 a 206 0.24 0.13 180 26 a 208 0.16 0.084 182 19.8 a 210 0.104 0.051 184 15.0 a 212 0.068 0.031 186 11.0 a 214 0.044 0.020 188 7.80 7.72 216 0.029 0.012 190 5.35 5.03 218 0.019 0.007 192 3.70 3.28 220 0.012 0.004 194 2.56 2.13 196 1.75 1.39 198 1.20 0.88 (a) No temperature dependence observed. Comments on Preferred Values The preferred values of the absorption cross-sections are those reported by Simon et al. (1988). They are in good agreement with the room temperature results of Chou et al. (1978). Hubrich and Stuhl (1980) reported higher values and a smaller temperature dependence. Photolysis is expected to occur with unit quantum efﬁciency by breaking of the C-Cl bond to yield CF ClCF + Cl. 2 2 References Chou, C. C., Milstein, R. J., Smith, W. S., Vera Ruiz, H., Molina, M. J. and Rowland, F. S.: J. Phys. Chem. 82, 1, 1978. Hubrich, C. and Stuhl, F.: J. Photochem. 12, 93, 1980. Simon, P. C., Gillotay, D., Vanlaethem-Meuree, N. and Wisemberg, J.: Ann. Geophysicae 6, 239, 1988. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4419 IV.A2.233 CF CF Cl + hν → products 3 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF CF Cl + hν → CF CF + Cl 346 346 3 2 3 2 Preferred Values Absorption cross-sections for CF CF Cl at 295 K to 225 K 3 2 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 172 5.65 190 0.27 174 4.05 192 0.19 176 2.85 194 0.13 178 2.05 196 0.090 180 1.45 198 0.063 182 1.05 200 0.044 184 0.75 202 0.031 186 0.53 204 0.021 188 0.38 Comments on Preferred Values The preferred values of the absorption cross-sections are those reported by Simon et al. (1988). In this study measurements were made down to 225 K, and the absorption cross-section values were found to be independent of temperature. They are in good agreement with the results of Hubrich and Stuhl (1980), who also made low temperature measurements. Earlier measurements of Chou et al. (1978) are 50% higher. Photolysis is expected to occur with unit quantum efﬁciency by breaking of the C-Cl bond to yield CF CF + Cl. 3 2 References Chou, C. C., Milstein, R. J., Smith, W. S., Vera Ruiz, H., Molina, M. J. and Rowland, F. S.: J. Phys. Chem. 82, 1, 1978. Hubrich, C. and Stuhl, F.: J. Photochem. 12, 93, 1980. Simon, P. C., Gillotay, D., Vanlaethem-Meuree, N. and Wisemberg, J.: Ann. Geophysicae 6, 239, 1988. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4420 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.234 CF CF CHCl + hν → products 3 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ.mol λ /nm threshold CF CF CHCl + hν → CF CF CHCl + Cl 335 (est) 360 3 2 2 3 2 Preferred Values Absorption cross-sections for CF CF CHCl at 298 K 3 2 2 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 160 269 200 16 165 197 205 6.9 170 183 210 2.9 175 191 215 1.2 180 177 220 0.46 185 129 225 0.17 190 74 230 0.065 195 37 240 0.011 Comments on Preferred Values The preferred values of the absorption cross-sections at 298 K are the values reported by Braun et al. (1991). In the same study, absorption cross-section measurements in the liquid phase were made over the wavelength range 205–270 nm (Braun et al., 1991). Correction factors were used to convert these liquid-phase values into gas-phase values. The combined set of gas-phase values for the wavelength range 170–270 nm were ﬁtted (Braun et al., 1991) with the expression: −2 −3 2 −5 3 log σ = -17.966 + 4.542× 10 X - 2.036× 10 X + 1.042× 10 X where X= (λ - 160 nm) Photolysis is expected to occur with unit quantum efﬁciency by breaking of the C-Cl bond to yield CF CF CHCl + Cl. 3 2 References Braun, W., Fahr, A., Klein, R., Kurylo, M. J. and Huie, R. E.: J. Geophys. Res. 96, 13009, 1991. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4421 IV.A2.235 CF ClCF CHFCl + hν → products 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CF ClCF CHFCl + hν → CF ClCF CHF + Cl 335 (est) 360 2 2 2 2 → CHFClCF CF + Cl 335 (est) 360 2 2 Preferred Values Absorption cross-sections for CF ClCF CHFCl at 298 K 2 2 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 160 188 185 9.1 165 145 190 3.5 170 91 195 1.5 175 47 200 0.63 180 21 205 0.33 210 0.25 Comments on Preferred Values The preferred values of the absorption cross-sections at 298 K are the values reported by Braun et al. (1991). In the same study, absorption cross-section measurements in the liquid phase were made over the wavelength range 205–270 nm (Braun et al., 1991). Correction factors were used to convert these liquid-phase values into gas-phase values. The combined set of gas-phase values for the wavelength range 170–270 nm were ﬁtted with the expression: −2 −3 2 −5 3 log σ = -17.714 - 2.175× 10 X - 1.484× 10 X + 1.147× 10 X where X= (λ - 160 nm) Photolysis is expected to occur with unit quantum efﬁciency by breaking of the C-Cl bond to yield CF ClCF CHF + Cl or 2 2 CHFClCF CF + Cl. 2 2 References Braun, W., Fahr, A., Klein, R., Kurylo, M. J. and Huie, R. E.: J. Geophys. Res. 96, 13009, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4422 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.236 HC(O)Cl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold HC(O)Cl + hν → HCO + Cl 340 (est) 350 Preferred Values Absorption cross-sections for HC(O)Cl at the band maxima (298 K, 1013 mbar of N , spectral resolution 0.7 nm) 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 236.1 3.8 280.2 2.4 241.5 4.9 282.7 2.3 247.3 5.6 285.3 1.64 251.4 5.4 286.8 1.04 253.7 6.0 288.0 0.86 256.1 5.6 289.4 0.97 258.2 5.8 292.2 0.81 260.2 6.0 294.9 0.46 263.5 5.1 296.7 0.32 265.7 5.3 298.1 0.22 267.9 5.2 299.5 0.25 269.1 3.9 302.3 0.172 270.2 3.5 305.2 0.080 271.4 4.0 308.1 0.027 273.8 4.1 309.3 0.021 276.3 3.4 311.1 0.020 277.7 2.4 314.1 0.013 278.9 2.1 316.7 0.008 318.7 0.007 Comments on Preferred Values The preferred values of the absorption cross-sections at 298 K are those reported by Libuda et al. (1990). These are the values of the absorption cross-sections at the absorption maxima and were measured at a spectral resolution of 0.7 nm. The absorption bands for λ > 265 nm became distinctly sharper when the spectral resolution was improved to 0.4 nm. The spectrum of HC(O)Cl is similar to that of HCHO but is shifted to shorter wavelengths by 45 nm. Although there have been no quantum yield studies of HC(O)Cl photolysis, it is reasonable to assume by analogy with the photolysis of C(O)Cl that the primary photolysis pathway proceeds by breaking of the C-Cl bond to yield HCO + Cl. References Libuda, H. G., Zabel, F., Fink, E. H. and Becker, K. H.: J. Phys. Chem. 94, 5860, 1990. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4423 IV.A2.237 C(O)FCl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold C(O)FCl + hν → FCO + Cl (1) 396 302 → ClCO + F (2) 485 247 → CO + F + Cl (3) 517 231 → CFCl + O( P) (4) 707 169 Quantum yield data Measurement Wavelength/nm Reference Comments 8 + 8 = 0.98± 0.09 193 Hermann et al., 1994 (a,b,c) 1 3 8 + 8 = 0.90± 0.05 210± 2.5 Nolle ¨ et al., 1999 (a,d,e) 1 3 8 + 8 = 0.85± 0.25 210 (a,b,e) 1 3 8 + 8 = 0.77± 0.33 225.5 (a,b,e) 1 3 8 + 8 = 0.71± 0.30 230 (a,b,e) 1 3 8 + 8 = 0.52± 0.14 248 (a,b,e) 1 3 Comments (a) The measured quantum yield is for the loss of C(O)FCl. The observed products were C(O)F (and in the study of Hermann et al. (1994), also CO). Product formation was explained using only channels (1) and (3), because decomposition of ClCO formed in channel (2) makes channel (2) equivalent to channel (3). Formation of C(O)F arises from the self-reaction of FCO radicals formed in channel (1), FCO + FCO→ C(O)F + CO. Channel (3) should not be accessible for wavelengths > 231 nm, and hence the quantum yield measured by Nolle et al. (1999) at 248 nm is expected to be that for channel (1). (b) Laser photolysis at 298 K. (c) The initial C(O)FCl pressure was in the range 7–11 mbar. In addition to experiments in the absence of diluent gas, experiments were carried out with added N diluent gas at total pressures of 100 and 900 mbar. The relative contribution of channels (1) and (3) depended on pressure with an equal contribution of the two channels at 900 mbar N . (d) Photolysis with a medium pressure mercury lamp-monochromator combination at 298 K. (e) The initial C(O)FCl pressure was∼ 5 mbar, with no added diluent gas. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4424 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values Absorption cross-sections for C(O)FCl at 298 K 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 186.0 15.6 207.3 10.8 187.8 14.0 209.4 9.9 189.6 13.4 211.6 9.0 191.4 12.9 213.9 7.9 193.2 12.7 216.2 6.9 195.1 12.5 218.6 5.8 197.0 12.4 221.0 4.8 199.0 12.3 223.5 3.8 201.0 12.5 226.0 2.9 203.0 12.0 228.6 2.2 205.1 11.5 231.2 1.6 Quantum yields for C(O)FCl photolysis at 298 K See Comments on Preferred Values Comments on Preferred Values The preferred values of the absorption cross-sections are those reported by Chou et al. (1977) over the wavelength range 186 to 199 nm and those reported by Nolle ¨ et al. (1993) at longer wavelengths. The spectrum shows little structure; the values −1 listed are averages over 500 cm intervals. Nolle ¨ et al. (1993) reported values over the wavelength range 200–260 nm and the temperature range 298–223 K. Their room temperature values are in good agreement with those of Chou et al. (1977). The effect of temperature on calculated photodissociation rates is negligible because no strong temperature dependence is observed in the atmospheric window region where photolysis occurs (190–230 nm). Hermann et al. (1994) and Nolle ¨ et al. (1999) photolyzed C(O)FCl at a number of speciﬁc wavelengths in the range 193–248 nm. Within the substantial measurement uncertainties, the overall quantum yield for loss of C(O)FCl decreases approximately linearly with wavelength from 1.0 at 193 nm to 0.5 at 248 nm. Until conﬁrmatory data are available, use of the quantum yields measured by Hermann et al. (1994) and Nolle ¨ et al. (1999) is recommended. Pulsed laser photolysis at 235 nm of C(O)FCl in a supersonic jet coupled to time-of-ﬂight spectroscopy showed that channel (1) is operative at this wavelength (Maul et al., 1999), and a value of 1H (C(O)FCl)[0 K] −1 = -(397± 15) kJ mol was obtained. References Chou, C. G., Crescentini, G., Vera-Ruiz, H., Smith, W. S. and Rowland, F.S.: Results presented at the 173rd American Chemical Society National Meeting, New Orleans, March, 1977. Hermann, M., Nolle, ¨ A. and Heydtmann, H.: Chem. Phys. Lett., 226, 559, 1994. Maul, C., Dietrich, C., Haas, T. and Gericke, K.-H.: Phys. Chem. Chem. Phys., 1, 1441, 1999. Nolle, ¨ A., Heydtmann, H., Meller, R. and Moortgat, G. K.: Geophys. Res. Lett., 20, 707, 1993. Nolle, ¨ A., Krumscheid, C. and Heydtmann, H.: Chem. Phys. Lett., 299, 561, 1999. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4425 IV.A2.238 C(O)Cl + hν → products Primary photochemical transitions ◦ −1 Reaction 1H /kJ mol λ /nm threshold C(O)Cl + hν → ClCO + Cl (1) 320 374 → CO + 2Cl (2) 352 340 → CCl + O( P) (3) 699 171 Preferred Values Absorption cross-sections for C(O)Cl at 298 K 20 2 20 2 λ/nm 10 σ /cm λ/nm 10 σ /cm 184.4 234 211.6 13.3 186.0 186 213.9 12.6 187.8 146 216.2 12.3 189.6 116 218.6 12.2 191.4 90.3 221.0 12.2 193.2 71.5 223.5 12.4 195.1 52.4 226.0 12.7 197.0 39.9 228.6 13.1 199.0 31.2 231.2 13.4 201.0 25.2 233.9 13.6 203.0 20.9 236.7 13.1 205.1 17.9 239.5 12.5 207.3 15.8 242.4 11.6 209.4 14.3 Quantum yield for C(O)Cl at 298 K 8(1) = 1.0 for λ > 184 nm. Comments on Preferred Values The preferred values of the absorption cross sections are those reported by Gillotay et al. (1993). The spectrum is a continuum; −1 the values listed are averaged over 500 cm intervals. The results of Gillotay et al. (1993) are in good agreement with the earlier results of Chou et al. (1977). Gillotay et al. (1993) reported values over the wavelength range 170–310 nm and the temperature range 210–295 K. The temperature effect is only signiﬁcant at longer wavelengths (λ > 250 nm). The observations of Wijnen (1961), Heicklen (1965) and earlier investigators (Calvert and Pitts, 1966) show that process (1) is the primary photolysis pathway. In the atmosphere, the overall photolysis proceeds by process (2) [i.e., ClCO decomposes to yield a second Cl atom] and the quantum yield for Cl atom formation will be 2.0. References Calvert, J. G. and Pitts, Jr., J. N.: ”Photochemistry,” page 231, John Wiley and Sons, Inc., New York, 1966. Chou, G. C., Crescentini, G., Vera-Ruiz, H., Smith, W. S. and Rowland, F. S.: Results presented at the 173rd American Chemical Society National Meeting, New Orleans, March, 1977. Gillotay, D., Simon, P. C. and Dierickx, L.: Aeronomica Acta, A368, 1993; Institut d’Aeronomie Spatiale de Belgique, Brussels, Belgium; presented at Quadrennial Ozone Symposium, Charlottesville, Virginia, June 1992. Heicklen, J.: J. Am. Chem. Soc., 87, 445, 1965. Wijnen, W. H.: J. Am. Chem. Soc., 83, 3014, 1961. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4426 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.239 CF ClCHO + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CF ClCHO + hν → CF Cl + HCO (1) 2 2 → CF ClCO + H (2) → CHF Cl + CO (3) Absorption cross-section data Wavelength range/nm References Comments 235-370 Rattigan et al., 1998 (a) Quantum yield data There are no reported quantum yield data. Comments (a) Absorption cross-sections were measured using a dual-beam diode array spectrometer over the temperature range 243– 298 K. The UV spectrum of diﬂuorochloroacetaldehyde shows a broad band, centered at 300 nm and extending out to 365 nm. Values of σ were given at 5 nm intervals at 298 K together with values of B in the expression ln σ (T ) = ln σ (298 K) + B(T -298). Preferred Values Absorption cross-sections for CF ClCHO at 298 K and their temperature dependence 20 2 4 −1a) Wavelength 10 σ (298 K)/cm 10 B/K 235 0.192 -29.0 240 0.408 -17.9 245 0.736 -13.5 250 1.25 -11.8 255 1.99 -10.7 260 3.02 -10.5 265 4.36 -10.4 270 6.05 -10.5 275 8.00 -9.96 280 10.1 -10.6 285 12.1 -10.2 290 14.0 -10.6 295 15.4 -9.54 300 16.3 -10.4 305 15.9 -7.09 310 15.4 -9.73 315 13.4 -8.32 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4427 20 2 4 −1 Wavelength 10 σ (298 K)/cm 10 B/K (a) 320 11.7 -7.71 325 9.24 -5.02 330 6.51 -3.03 335 4.76 -2.83 340 2.84 -2.84 345 1.52 14.0 350 0.711 37.3 355 0.148 68.1 360 0.036 75.8 365 0.012 52.9 370 0.003 63.1 (a) ln σ (T ) = ln σ (298 K) + B(T -298) Quantum yield for CF ClCHO No recommendation. Comments on Preferred Values The preferred values for the cross-sections are those reported by Rattigan et al. (1998). There are no data on the quantum yields but, by analogy with acetaldehyde which shows a similar absorption spectrum, photodissociation is expected to be predominantly by channel (1). References Rattigan, O. V., Wild, O. and Cox, R. A.: J. Photochem. Photobiol. A: Chem., 112, 1, 1998. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4428 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.240 CFCl CHO + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CFCl CHO + hν → CFCl + HCO (1) 2 2 → CFCl CO + H (2) → CHFCl + CO (3) Absorption cross-section data Wavelength range/nm References Comments 235-370 Rattigan et al., 1998 (a) Quantum yield data There are no reported quantum yield data. Comments (a) Absorption cross-sections were measured using a dual-beam diode array spectrometer over the temperature range 243– 298 K. The UV spectrum of diﬂuorochloroacetaldehyde shows a broad band, centered at 300 nm and extending out to 365 nm. Values of σ were given at 5 nm intervals at 298 K together with values of B in the expression ln σ (T ) = ln σ (298 K) + B(T -298). Preferred Values Absorption cross-sections for CFCl CHO at 298 K and their temperature dependence 20 2 4 −1 Wavelength 10 σ (298 K)/cm 10 B/K (a) 235 0.402 136.0 240 0.502 87.0 245 1.080 30.6 250 1.597 6.41 255 2.391 1.24 260 3.483 -6.12 265 4.869 -7.55 270 6.527 -8.11 275 8.351 -8.28 280 10.1 -8.04 285 11.8 -7.82 290 13.0 -6.89 295 13.7 -6.41 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4429 20 2 4 −1 Wavelength 10 σ (298 K)/cm 10 B/K (a) 300 13.6 -4.50 305 12.9 -2.93 310 11.6 1.73 315 9.80 2.70 320 7.93 6.97 325 5.61 12.2 330 3.89 15.6 335 2.46 24.6 340 1.26 36.5 345 0.628 58.1 350 0.254 84.9 355 0.052 92.8 360 0.017 93.2 365 0.007 103.2 370 0.002 138.3 (a) ln σ (T ) = ln σ (298 K) + B(T -298) Quantum yield for CFCl CHO No recommendation. Comments on Preferred Values The preferred values for the cross-sections are those reported by Rattigan et al. (1998). There are no data on the quantum yields but, by analogy with acetaldehyde which shows a similar absorption spectrum, photodissociation is expected to be predominantly by channel (1). References Rattigan, O. V., Wild, O. and Cox, R. A.: J. Photochem. Photobiol. A: Chem., 112, 1, 1998. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4430 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A2.241 CCl CHO + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CCl CHO + hν → CCl + HCO (1) 3 3 → CCl CO + H (2) → CHCl + CO (3) → CCl CHO + Cl (4) Absorption cross-section data Wavelength range/nm References Comments 200-340 Rattigan et al., 1993 (a) 200-370 Rattigan et al., 1998 (b) 200-345 Talukdar et al., 2001 (c) Quantum yield data Measurement Wavelength/nm Reference Comments 8[H] = 0.04± 0.005 193 Talukdar et al., 2001 (d) 8[O( P)] <0.02 248 8[H] <0.01 248 8[O( P)] <0.01 308 8[H] <0.002 308 8[Cl] = 1.3± 0.3 308 8[-CCl CHO] = 1.00± 0.05 290-400 Wenger et al., 2004 (e) Comments (a) Absolute absorption cross-sections were measured using a dual-beam diode array spectrometer over the temperature range 240–300 K. The UV spectrum of trichloroacetaldehyde shows a broad band, centered at 290 nm and extending out to 360 nm. Values of σ were given at 5 nm intervals at 296 K and 243 K. A second absorption band appears at <230 nm. (b) Absolute absorption cross-sections were measured using a dual-beam diode array spectrometer over the temperature range 243–298 K. Values of σ were given at 5 nm intervals at 298 K together with the values of B in the expression ln σ (T ) = ln σ (298 K) + B(T -298). (c) Absolute absorption cross-sections were measured using a diode array spectrometer over the temperature range 240–360 K. Values of σ were listed at 298 K at 2 nm intervals, together with the values of B in the expression ln σ (T ) = ln σ (298 K) + B(T -298). (d) Determined from pulsed laser photolysis of CCl CHO with detection of H, O( P) and Cl atoms by resonance ﬂuorescence. Experiments were carried out at 298± 2 K, and the H, O( P) and Cl atom signals were placed on an absolute basis by use of photolysis of HBr (193 nm) or CH SH (248 and 308 nm) as reference compounds for H atom formation, photolysis of O in the presence of N at 248 and 308 nm as a reference compound for production of O( P) atoms, and photolysis of Cl 3 2 2 at 308 nm as a reference compound for production of Cl atoms. Because Cl atoms react with CCl CHO, their yield was obtained by extrapolation to zero time. Cl atom formation was shown to be a primary process. Photolysis of CCl CHO at 248 nm in the presence of O led to the formation of CO and C(O)Cl , with no formation of CHCl (thereby ruling out 2 2 3 the occurrence of channel (3) at 248 nm). Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4431 (e) Determined from the photolysis of CCl CHO in the∼200 m volume EUPHORE chamber under natural sunlight condi- tions at 298± 5 K. Cyclohexane was added to scavenge Cl atoms and SF was added to monitor dilution and loss through leakage. CCl CHO was monitored by FTIR spectroscopy and GC. The formation yield of Cl atoms was obtained from the amounts of cyclohexane consumed during the photolyses. The measured decay rates of CCl CHO, corrected for dilution, were compared to the calculated decay rates for a photodissociation quantum yield of 1.00. Preferred Values Absorption cross-sections of CCl CHO at 298 K and their temperature dependence 20 2 4 −1 Wavelength 10 σ (298 K)/cm 10 B/K (a) 200 186.9 22.0 202 152.5 23.9 204 121.8 27.2 206 95.7 30.6 208 73.8 34.1 210 56.3 37.5 212 42.6 40.9 214 31.8 44.0 216 23.8 47.2 218 17.7 50.2 220 13.1 52.9 222 9.75 55.6 224 7.24 57.6 226 5.39 59.0 228 4.06 60.4 230 3.07 60.5 232 2.39 59.5 234 1.90 55.9 236 1.62 49.2 238 1.43 41.6 240 1.39 33.0 242 1.41 24.0 244 1.53 16.4 246 1.66 10.4 248 1.91 6.50 250 2.18 3.73 252 2.54 1.50 254 2.92 0.324 256 3.36 -0.569 258 3.84 -0.877 260 4.35 -1.23 262 4.90 -1.65 264 5.48 -1.62 266 6.07 -1.50 268 6.68 -1.41 270 7.28 -1.22 272 7.88 -1.07 274 8.46 -0.931 276 8.99 -0.584 278 9.49 -0.412 280 9.94 -0.481 282 10.3 -0.235 284 10.6 0.242 286 10.8 0.475 288 10.9 0.750 290 10.9 1.09 292 10.8 1.51 294 10.6 1.96 296 10.3 2.38 298 9.92 2.71 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4432 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 20 2 4 −1 Wavelength 10 σ (298 K)/cm 10 B/K (a) 300 9.25 3.07 302 8.77 3.60 304 8.17 4.37 306 7.50 5.25 308 6.86 6.10 310 6.18 6.91 312 5.58 7.90 314 4.98 9.30 316 4.33 11.2 318 3.68 13.2 320 3.09 15.1 322 2.51 16.7 324 2.09 18.5 326 1.76 21.1 328 1.43 25.0 330 1.12 30.3 332 0.849 36.6 334 0.590 43.3 336 0.373 49.8 338 0.261 55.6 340 0.188 60.2 342 0.136 65.0 344 0.100 69.0 (a) ln σ (T ) = ln σ (298 K) + B(T -298) Quantum yield for CCl CHO 8(4) = 1.0 over the wavelength range 290–400 nm. Comments on Preferred Values The preferred values for the cross-sections are those reported by Talukdar et al. (2001), which are in excellent agreement with the earlier data of Rattigan et al. (1998) except at 230–250 nm where the Rattigan et al. (1998) cross-sections are somewhat lower. The preferred quantum yield is based on the studies of Talukdar et al. (2001) at 308 nm and of Wenger et al. (2004) using natural sunlight photolysis over the wavelength region 290–400 nm. Wenger et al. (2004) observed the formation of C(O)Cl , CO and Cl atoms from the photolysis of CCl CHO at 290–400 nm, with molar yields of 0.83± 0.04, 1.01± 0.05 and 2 3 1.18 ± 0.06, respectively, which when combined with the data of Talukdar et al. (2001) indicates that the dominant primary process at λ > 290 nm is to form Cl + CCl CHO [channel (4)]. References Rattigan, O. V., Wild, O. and Cox, R. A.: J. Photochem. Photobiol. A: Chem., 112, 1, 1998. Rattigan, O. V., Wild, O., Jones, R. L. and Cox, R. A.: J. Photochem. Photobiol. A: Chem., 73, 1 1993. Talukdar, R. K., Mellouki, A., Burkholder, J. B., Gilles, M. K., Le Bras, G. and Ravishankara, A. R.: J. Phys. Chem. A, 105, 5188, 2001. Wenger, J. C., Le Calv, S., Sidebottom, H. W., Wirtz, K., Martn Reviejo, M. and Franklin, J. A.: Environ. Sci. Technol., 38, 831, 2004. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4433 IV.A2.242 CF C(O)Cl + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CF C(O)Cl + hν → CF + ClCO (1) 3 3 → CF CO + Cl (2) Absorption cross-section data Wavelength range/nm References Comments 200-330 Meller and Moortgat, 1997 (a) Quantum yield data Measurement Wavelength/nm Reference Comments 8 + 8 = 0.95± 0.05 254 Meller and Moortgat, 1997 (b) 1 2 8 + 8 = 1.01± 0.11 193 Maricq and Szente, 1995 (c) 1 2 8 + 8 = 1.01± 0.11 248 1 2 8 + 8 = 0.98± 0.13 254-280 Weibel et al., 1995 (d) 1 2 Comments (a) Absolute absorption cross-sections were measured using a diode array spectrometer over the temperature range 223–298 K. The UV spectrum of triﬂuoroacetyl chloride shows two overlapping bands, the ﬁrst having a maximum at 255 nm (σ −19 2 −1 = 6.87 × 10 cm molecule ), and the second at λ < 200 nm. There is signiﬁcant absorption at wavelengths > 300 nm, where the cross-sections become increasingly temperature dependent. The estimated overall errors in the values of σ were± 3% over the wavelength range 200–310 nm, increasing to± 20% for longer wavelengths where the cross-sections (and hence absorptions) are low. Values of σ were presented at 2 nm intervals at 223 K, 248 K, 273 K and 298 K. The 2 3 4 measured absorption cross-sections were ﬁt to the equation lnσ (λ, T ) = A + A λ + A λ + A λ + A λ + (B + B λ + 0 1 2 3 4 0 1 2 3 4 B λ + B λ + B λ )(T - 273), with the following values which ﬁt the measurements to within 3% throughout most of 2 3 4 the spectrum, but with larger errors in the range 220–230 nm (up to 6% error) and at >300 nm (up to 20% error at 330 nm): λ = 200-220 nm λ = 218-330 nm 4 1 A -2.0111750× 10 -8.8912918× 10 2 −1 A 3.1757333× 10 9.6418661× 10 −3 A -2.5671017 -5.4370794× 10 −3 −5 A 7.8520098× 10 1.4975946× 10 −6 −7 A -8.9707718× 10 -1.6768324× 10 B 3.0306320× 10 3.7950580 −2 B -5.8082356 -5.9114731× 10 −2 −4 B 4.1715164× 10 3.4406419× 10 −4 −7 B -1.3306565× 10 -8.8699856× 10 −7 −10 B 1.5906451× 10 8.5483894× 10 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4434 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry (b) Average of measurements of the overall loss of CF C(O)Cl during photolysis in N . Measurements of the photodissoci- 3 2 ation quantum yield of CF C(O)Cl in air at total pressures of 67–1013 mbar showed no effect of total pressure or of the presence of O . (c) Pulsed laser photolysis of CF C(O)Cl-C H -O -N mixtures at a total pressure of 160 mbar, with detection of CF O 3 2 6 2 2 3 2 radicals by time-resolved UV spectroscopy and of HCl by IR spectroscopy. CF O radicals were formed from CF 3 2 3 radicals and HCl was formed from Cl + C H → HCl + C H . The system was calibrated by photolysis of CH Cl at 193 2 6 2 5 3 nm and of Cl at 248 nm instead of CF C(O)Cl, with the assumption that the photodissociation quantum yields of CH Cl 2 3 3 and Cl are unity. (d) Quantum yields derived from the amounts of C F and CF Cl formed from irradiating CF C(O)Cl at 254 and 280 nm 2 6 3 3 (high pressure mercury arc-monochromator combination). Actinometry was performed with potassium ferrioxalate solu- tion. It was observed that (2[C F ] + [CF Cl])/[CO] = 0.99± 0.05, consistent with formation of CF radicals, Cl atoms 2 6 3 3 and CO followed by the combination reactions CF + CF → C F and CF + Cl → CF Cl. Hence 8(-CF Cl(O)Cl) = 3 3 2 6 3 3 3 28(C F ) + 8(CF Cl). 2 6 3 Preferred Values Absorption cross-sections of CF COCl at 298 K and their temperature dependence 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm 298 K 223 K 200 50.16 45.83 202 30.47 26.56 204 17.70 14.63 206 9.960 7.830 208 5.567 4.197 210 3.274 2.461 212 2.102 1.662 214 1.620 1.361 216 1.442 1.343 218 1.484 1.421 220 1.665 1.641 222 1.896 1.845 224 2.201 2.184 226 2.544 2.538 228 2.904 2.901 230 3.278 3.261 232 3.685 3.646 234 4.080 4.025 236 4.505 4.456 238 4.902 4.852 240 5.283 5.223 242 5.629 5.553 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4435 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm 298 K 223 K 244 5.957 5.900 246 6.271 6.177 248 6.503 6.411 250 6.694 6.577 252 6.799 6.679 254 6.863 6.712 256 6.858 6.674 258 6.786 6.586 260 6.599 6.383 262 6.393 6.148 264 6.159 5.875 266 5.859 5.567 268 5.510 5.219 270 5.120 4.814 272 4.726 4.396 274 4.306 3.965 276 3.876 3.564 278 3.444 3.133 280 3.035 2.724 282 2.630 2.304 284 2.253 1.931 286 1.907 1.619 288 1.593 1.334 290 1.324 1.090 292 1.082 0.8672 294 0.8670 0.6739 296 0.6811 0.5117 298 0.5282 0.3977 300 0.4038 0.2978 302 0.3035 0.2178 304 0.2214 0.1520 306 0.1580 0.1018 308 0.1087 0.0642 310 0.0722 0.0376 312 0.0472 0.0211 314 0.0301 0.0115 316 0.0189 0.0061 318 0.0123 0.0033 320 0.0084 0.0019 322 0.0057 324 0.0037 326 0.0025 328 0.0017 Quantum yield for CF COCl 8 + 8 = 1.0 over the wavelength range 200–325 nm. 1 2 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4436 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The data of Meller and Moortgat (1997) are in good agreement with the earlier results of Rattigan et al. (1993) and Jemi- Alade et al. (1991), except in the region of minimum absorption near 220 nm. The preferred values for the cross-sections are those reported by Meller and Moortgat (1997). The quantum yield is based on the measurements of Meller and Moortgat (1997), Marciq and Szente (1995) and Weibel et al. (1995). Maricq and Szente (1995) concluded that at 193 and 248 nm photolysis proceeds via channel (1), with the CF CO radical dissociating totally at 193 nm and∼ 86% of the time at 248 nm. This interpretation (Maricq and Szente, 1995) is reasonably consistent with the product data of Weibel et al. (1995) for the wavelength range 254–280 nm and of Malanca et al. (1997, 1998) at 254 nm. References Jemi-Alade, A. A., Lightfoot, P. D. and Lesclaux, R.: Chem. Phys. Lett., 179, 119, 1991. Malanca, F. E., Arguello, ¨ G. A. and Staricco, E. H.: J. Photochem. Photobiol. A: Chem., 103, 19, 1997. Malanca, F. E., Arguello, ¨ G. A., Staricco, E. H. and Wayne, R. P.: J. Photochem. Photobiol. A: Chem., 117, 163, 1998. Maricq, M. M. and Szente, J. J.: J. Phys. Chem., 99, 4554, 1995. Meller, R. and Moortgat, G. K.: J. Photochem. Photobiol. A: Chem., 108, 105, 1997. Rattigan, O. V., Wild, O., Jones, R. L. and Cox, R. A.: J. Photochem. Photobiol. A: Chem., 73, 1, 1993. Weibel, D. E., Arguello, ¨ G. A., de Staricco, E. R. and Staricco, E. H.: J. Photochem. Photobiol. A: Chem., 86, 27, 1995. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4437 Appendix 3: BrO Reactions IV.A3.243 HO + CH Br→ H O + CH Br 3 2 2 ◦ −1 1H = -71.9 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (3.5± 0.8)× 10 296± 2 Howard and Evenson, 1976 DF-LMR −13 7.93× 10 exp[-(889± 59)/T ] 244-350 Davis et al., 1976 FP-RF −14 (4.14± 0.43)× 10 298 −12 2.35× 10 exp[-(1300± 150)/T ] 233-379 Mellouki et al., 1992 PLP-LIF −14 (2.96± 0.36)× 10 298 −12 5.79× 10 exp[-(1560± 150)/T ] 250-400 Zhang et al., 1992 FP-RF −14 (3.08± 0.47)× 10 298 −12 1.86× 10 exp[-(1230± 150)/T ] 248-390 Chichinin et al., 1994 DF-EPR −14 (3.03± 0.45)× 10 298 Relative Rate Coefﬁcients −18 2 5.43× 10 T exp[-(812± 46)/T ] 298-360 Hsu and Demore, 1994 RR (a) −14 3.16× 10 298 Comments (a) HO radicals were generated from the UV photolysis of O in the presence of water vapor, in O -H O-CH Br-CH CHF - 3 3 2 3 3 2 O -N mixtures. The concentrations of CH Br and CH CHF were measured by FTIR spectroscopy. The measured rate 2 2 3 3 2 coefﬁcient ratio of k(HO + CH Br)/k(HO + CH CHF ) = (1.94± 0.28) exp[-(232± 46)/T ] is placed on an absolute basis 3 3 2 −18 2 3 −1 −1 by use of a rate coefﬁcient of k(HO + CH CHF ) = 2.80× 10 T exp(-580/T ) cm molecule s (IUPAC, current 3 2 recommendation). Preferred Values −14 3 −1 −1 k = 2.9× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.7× 10 exp(-1215/T ) cm molecule s over the temperature range 240-300 K. Reliability 1 log k =± 0.08 at 298 K. 1 (E/R) =± 150 K. Comments on Preferred Values The recent absolute rate coefﬁcient measurements of Mellouki et al. (1992), Zhang et al. (1992) and Chichinin et al. (1994), which are in excellent agreement, are signiﬁcantly lower than those previously determined by Howard and Evenson (1976) and Davis et al. (1976). The relative rate coefﬁcients of Hsu and DeMore (1994) are also in excellent agreement with the absolute rate coefﬁcients of Mellouki et al. (1992), Zhang et al. (1992) and Chichinin et al. (1994). A unit-weighted least- squares analysis of the rate coefﬁcients of Mellouki et al. (1992), Zhang et al. (1992) and Chichinin et al. (1992), using the www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4438 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 2 −18 2 3 −1 −1 three parameter expression k = CT exp(-D/T ), leads to k = 3.44 × 10 T exp(-687 /T ) cm molecule s over the temperature range 233–400 K. The preferred Arrhenius expression, k = A exp(-B/T ), is centered on a mid-range temperature, 2 2 T , of 265 K and is derived from three parameter expression with A = C e T and B = D+ 2T . m m References Chichinin, A., Teton, S., Le Bras, G. and Poulet, G.: J. Atmos. Chem. 18, 239, 1994. Davis, D. D., Machado, G., Conaway, B. C., Oh, Y. and Watson, R. T.: J. Chem. Phys., 65, 1268, 1976. Howard, C. J. and Evenson, K. M.: J. Chem. Phys., 64, 197, 1976. Hsu, K.-J. and DeMore, W. B.: Geophys. Res. Lett., 21, 805, 1994. Mellouki, A., Talukdar, R. K., Schmoltner, A.-M., Gierczak, T., Mills, M. J., Solomon, S. and Ravishankara, A. R.: Geophys. Res. Lett., 19, 2059, 1992. Zhang, Z., Saini, R. D., Kurylo, M. J. and Huie, R. E.: Geophys. Res. Lett., 19, 2413, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4439 IV.A3.244 HO + CH Br → H O + CHBr 2 2 2 2 ◦ −1 1H = -79.6 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 1.91× 10 exp[-(840± 100)/T ] 243-380 Mellouki et al., 1992 PLP-LIF −13 (1.13± 0.15)× 10 298 −12 1.51× 10 exp[-(720± 60)/T ] 288-368 Zhang et al., 1997 DF-RF −13 (1.33± 0.14)× 10 Relative Rate Coefﬁcients −14 (9.7± 0.6)× 10 298 Orlando et al., 1996 RR (a) −12 1.51× 10 exp[-(715± 39)/T ] 293-375 DeMore, 1996 RR (b) −13 1.37× 10 298 Comments (a) HO radicals were generated by the photolysis of O in the presence of H O, and acetone was used as the reference com- 3 2 pound. CH Br and acetone were monitored by FTIR spectroscopy, and a rate coefﬁcient ratio of k(HO + CH Br )/k(HO 2 2 2 2 + acetone) = 0.54 ± 0.03 was determined. This rate coefﬁcient ratio is placed on an absolute basis by use of a rate −13 3 −1 −1 coefﬁcient of k(HO + acetone) = 1.8× 10 cm molecule s at 298 K (IUPAC, current recommendation). (b) HO radicals were generated by the photolysis of O at 254 nm in the presence of H O, and CH Cl was used as the 3 2 2 2 reference compound. CH Br and CH Cl were monitored by FTIR spectroscopy, and a rate coefﬁcient ratio of k(HO + 2 2 2 2 CH Br )/k(HO + CH Cl ) = 0.84 exp[(145± 39)/T ] was determined. This rate coefﬁcient ratio is placed on an absolute 2 2 2 2 −12 3 −1 −1 basis by use of a rate coefﬁcient of k(HO + CH Cl ) = 1.8 × 10 exp(-860/T ) cm molecule s (IUPAC, current 2 2 recommendation). Preferred Values −13 3 −1 −1 k = 1.1× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.5× 10 exp(-775/T ) cm molecule s over the temperature range 240-300 K. Reliability 1 log k =± 0.15 at 298 K. 1 (E/R) =± 200 K. Comments on Preferred Values The room temperature rate coefﬁcients of Mellouki et al. (1992), Orlando et al. (1996), DeMore (1996) and Zhang et al. −14 3 −1 −1 −13 3 −1 −1 (1997) range from 9.7 × 10 cm molecule s to 1.43 × 10 cm molecule s . The relative rate coefﬁcients of DeMore (1996) and the absolute rate coefﬁcients of Zhang et al. (1997), obtained over the temperature range∼290–370 K, are systematically higher than the absolute rate data of Mellouki et al. (1992), by∼20% at 290 K and∼10% at 370 K. Because the Mellouki et al. (1992) study included measurements down to signiﬁcantly lower temperatures than did the other studies, and their room temperature rate coefﬁcient is in between those of Orlando et al. (1996), DeMore (1996) and Zhang et al. (1997), www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4440 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry the Mellouki et al. (1992) study is used as the basis for the preferred values. While an Arrhenius plot of the Mellouki et al. (1992) data shows little evidence for curvature, the absolute rate coefﬁcients of Mellouki et al. (1992) have been ﬁtted to the 2 −18 2 3 −1 −1 three-parameter expression k = CT exp(-D/T ), resulting in k = 2.86× 10 T exp(-246/T ) cm molecule s over the temperature range 243–380 K. The preferred Arrhenius expression, k = A exp(B/T ), is centered on a mid-range temperature, 2 2 T , of 265 K and is derived from three parameter expression with A = C e T and B = D+ 2T . m m References DeMore, W. B.: J. Phys. Chem., 100, 5813, 1996. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Mellouki, A., Talukdar, R. K., Schmoltner, A.-M., Gierczak, T., Mills, M. J., Solomon, S. and Ravishankara, A. R.: Geophys. Res. Lett., 19, 2059, 1992. Orlando, J. J., Tyndall, G. S., Wallington, T. J. and Dill, M.: Int. J. Chem. Kinet., 28, 433, 1996. Zhang, Z., Zhong, J. and Qiu, L.: J. Atmos. Chem., 27, 209, 1997. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4441 IV.A3.245 HO + CHF Br→ H O + CF Br 2 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 4.4× 10 exp[-(1050± 400)/T ] 275-420 Brown et al., 1990 DF-RF −14 (1.3± 0.3)× 10 298 −13 7.4× 10 exp[-(1300± 100)/T ] 233-432 Talukdar et al., 1991 PLP-LIF/DF-LMR −14 (1.06± 0.08)× 10 298 −13 9.3× 10 exp[-(1326± 33)/T ] 298-460 Orkin and Khamaganov, 1993 DF-EPR −14 (1.10± 0.09)× 10 298 Relative Rate Coefﬁcients −21 2.82 6.11× 10 T exp[-(527± 31)/T ] 283-368 Hsu and DeMore, 1995 RR (a) −15 9.9× 10 298 Comments (a) HO radicals were generated by the UV photolysis of O in the presence of water vapor in O -H O-CHF Br-CH -O -N 3 3 2 2 4 2 2 mixtures. The concentrations of CHF Br and CH were measured by FTIR spectroscopy. The measured rate coefﬁcient 2 4 ratio of k(HO + CHF Br)/k(HO + CH ) = (0.33± 0.03) exp[(460± 31)/T ] is placed on an absolute basis by using a rate 2 4 −20 2.82 3 −1 −1 coefﬁcient of k(HO + CH ) = 1.85× 10 T exp(-987/T ) cm molecule s (IUPAC, current recommendation). Preferred Values −14 3 −1 −1 k = 1.0× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 7.9× 10 exp(-1300/T ) cm molecule s over the temperature range 230-360 K. Reliability 1 log k =± 0.10 at 298 K. 1 (E/R) =± 150 K. Comments on Preferred Values The absolute coefﬁcients of Talukdar et al. (1991) and Orkin and Khamaganov (1993), and the relative rate data of Hsu and DeMore (1995) are in excellent agreement at 298 K. The absolute rate coefﬁcients of Brown et al. (1990) are signiﬁcantly higher and are not used in the evaluation. Above room temperature, the absolute rate coefﬁcients of Talukdar et al. (1991) are lower than those of Orkin and Khamaganov (1993): at 430 K the rate coefﬁcient of Talukdar et al. (1991) is 20% lower than that of Orkin and Khamaganov (1993). The data of Hsu and DeMore (1995) display a slightly higher temperature dependence than those observed in the absolute rate studies at temperatures up to 370 K. The preferred 298 K rate coefﬁcient is the mean of the absolute rate coefﬁcients of Talukdar et al. (1991), Orkin and Khamaganov (1993) and the relative rate coefﬁcient Hsu and DeMore (1995). The temperature dependence is that measured by Talukdar et al. (1991), with the pre-exponential factor adjusted to ﬁt the 298 K preferred value. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4442 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Brown, A. C., Canosa-Mas, C. E., Parr, A. D., Rothwell, K. and Wayne, R. P.: Nature 347, 541, 1990. Hsu, K.-J. and DeMore, W. B.: J. Phys. Chem. 99, 1235, 1995. IUPAC: http://www.iupac-kinetic.ch.cam.ac.uk/, 2007. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem. 16, 169, 1993. Talukdar, R., Mellouki, A., Gierczak, T., Burkholder, J. B., McKeen, S. A. and Ravishankara, A. R.: Science 252, 693, 1991. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4443 IV.A3.246 HO + CF Br→ products Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −16 <1.2× 10 298 Burkholder et al., 1991 DF-LMR/PLP-LIF −17 <2.0× 10 298 Orkin and Khamaganov, 1993 DF-EPR −16 <4.0× 10 460 Preferred Values −18 3 −1 −1 k < 6.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k < 1.0× 10 exp(-3600/T ) cm molecule s over the temperature range 250-460 K. Comments on Preferred Values Only upper limits to the rate coefﬁcients were observed in the studies of Burkholder et al. (1991) and Orkin and Khamaganov −12 3 −1 −1 (1993). The A-factor for the reaction was estimated to be ∼1 × 10 cm molecule s . The lower limit for E/R was estimated to be >3600 K based on the upper limit value of the rate coefﬁcient determined by Orkin and Khamaganov (1993) at 460 K. The upper limit for the rate coefﬁcient at 298 K is obtained using these parameters. References Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar, R., McKeen, S. A., Orlando, J. J., Vaghjiani, G. L. and Ravishankara, A. R.: J. Geophys. Res. 96, 5025, 1991. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem. 16, 169, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4444 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.247 HO + CF ClBr→ products Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −15 <1× 10 293 Clyne and Holt, 1979 DF-RF −16 <2× 10 293 Burkholder et al., 1991 DF-LMR −17 <9× 10 297 PLP-LIF −17 <7× 10 373 PLP-LIF −16 <2× 10 424 DF-LMR Preferred Values −17 3 −1 −1 k < 1× 10 cm molecule s at 298 K. −12 3 −1 −1 k < 1× 10 exp(-3450/T ) cm molecule s over the temperature range 250-380 K. Comments on Preferred Values The studies of Clyne and Holt (1979) and Burkholder et al. (1991) both observed no reaction of HO radicals with CF ClBr. −12 The preferred upper limit Arrhenius expression is obtained from an assumed Arrhenius pre-exponential factor of 1 × 10 3 −1 −1 cm molecule s and the upper limit rate coefﬁcient at 373 K measured by Burkholder et al. (1991). The resulting upper limit Arrhenius expression yields a 298 K upper limit rate coefﬁcient which is consistent with the room temperature data of Clyne and Holt (1979) and Burkholder et al. (1991). References Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar, R., McKeen, S. A., Orlando, J. J., Vaghjiani, G. L. and Ravishankara, A. R.: J. Geophys. Res., 96, 5025, 1991. Clyne, M. A. A. and Holt, P. M.: J. Chem. Soc. Faraday Trans. 2, 75, 569, 1979. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4445 IV.A3.248 HO + CF Br → products 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −16 <4.0× 10 384-424 Burkholder et al., 1991 DF-LMR/PLP-LIF −16 <5.0× 10 298 Preferred Values −16 3 −1 −1 k < 5.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k < 1.0× 10 exp(-2200/T ) cm molecule s over the temperature range 250-460 K. Comments on Preferred Values The preferred upper limit is based on the sole study of Burkholder et al. (1991). The preferred upper limit to the rate coefﬁcient −16 3 −1 −1 at 298 K is conﬁrmed by the values of k < 4× 10 cm molecule s measured at 384 and 424 K. The A-factor for the −12 3 −1 −1 reaction was estimated to be∼1× 10 cm molecule s . The lower limit for E/R was estimated to be > 2200 K based on the upper limit value of the rate coefﬁcient determined by Burkholder et al. (1991) at 298 K. References Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar, R., McKeen, S. A., Orlando, J. J., Vaghjiani, G. L. and Ravishankara, A. R.: J. Geophys. Res. 96, 5025, 1991. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4446 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.249 HO + CF CH Br→ H O + CF CHBr 3 2 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 8.5× 10 exp[-(1113± 35)/T ] 298-460 Orkin and Khamaganov, 1993 DF-EPR −14 (2.05± 0.16)× 10 298 −12 1.39× 10 exp[-(1350± 195)/T ] 280-353 Nelson et al., 1993 DF-LIF −14 (1.45± 0.13)× 10 294 Preferred Values −14 3 −1 −1 k = 1.6× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.4× 10 exp(-1340/T ) cm molecule s over the temperature range 280-460 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The rate coefﬁcients of Nelson et al. (1993) are∼15-25% lower than those of Orkin and Khamaganov (1993) over the temper- ature range common to both studies (298–353 K). A least-squares analysis of the rate coefﬁcients of Orkin and Khamaganov (1993) and Nelson et al. (1993) yields the preferred Arrhenius expression. References Nelson Jr., D. D., Zahniser, M. S. and Kolb, C. E.: Geophys. Res. Lett. 20, 197, 1993. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem. 16, 169, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4447 IV.A3.250 HO + CF CHFBr→ H O + CF CFBr 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 1.13× 10 exp[-(1250± 364)/T ] 279-423 Brown et al., 1990 DF-RF −14 (1.7± 0.3)× 10 298 −13 7.2× 10 exp[-(1111± 32)/T ] 298-460 Orkin and Khamaganov, 1993 DF-EPR −14 (1.75± 0.17)× 10 298 Preferred Values −14 3 −1 −1 k = 1.7× 10 cm molecule s at 298 K. −13 3 −1 −1 k = 8.1× 10 exp(-1155/T ) cm molecule s over the temperature range 270-460 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The absolute rate coefﬁcients of Brown et al. (1990) and Orkin and Khamaganov (1993) are in good agreement. A least-squares analysis of the rate coefﬁcients of Brown et al. (1990) and Orkin and Khamaganov (1993) yields the preferred values. References Brown, A. C., Canosa-Mas, C. E., Parr, A. D., Rothwell, K. and Wayne, R. P.: Nature 347, 541, 1990. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem. 16, 169, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4448 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.251 HO + CF CHClBr→ H O + CF CClBr 3 2 3 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −14 (6.0± 0.4)× 10 303 Brown et al., 1989; 1990 DF-RF −12 1.28× 10 exp[-(995± 38)/T ] 298-460 Orkin and Khamaganov, 1993 DF-EPR −14 (4.50± 0.40)× 10 298 Preferred Values −14 3 −1 −1 k = 4.6× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 1.2× 10 exp(-970/T ) cm molecule s over the temperature range 290-460 K. Reliability 1 log k =± 0.20 at 298 K. 1 (E/R) =± 300 K. Comments on Preferred Values The rate coefﬁcient of Brown et al. (1989; 1990) at 303 K is∼25% higher than that calculated from the Arrhenius expression of Orkin and Khamaganov (1993). A least-squares analysis of the rate coefﬁcients of Orkin and Khamaganov (1993) leads to the preferred Arrhenius expression. References Brown, A. C., Canosa-Mas, C. E., Parr, A. D., Pierce, J. M. T. and Wayne, R. P.: Nature, 341, 635, 1989. Brown, A. C., Canosa-Mas, C. E., Parr, A. D. and Wayne, R. P.: Atmos. Environ., 24A, 2499, 1990. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem., 16, 169, 1993. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4449 IV.A3.252 HO + CF BrCF Br→ products 2 2 Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −16 <1.5× 10 298 Burkholder et al., 1991 DF-LMR/PLP-LIF −17 <2.0× 10 298 Orkin and Khamaganov, 1993 DF-EPR −16 <4.0× 10 460 Preferred Values −18 3 −1 −1 k < 6× 10 cm molecule s at 298 K. −12 3 −1 −1 k < 1× 10 exp(-3600/T ) cm molecule s over the temperature range 250-460 K. Comments on Preferred Values Only upper limits to the rate coefﬁcients were observed in the studies of Burkholder et al. (1991) and Orkin and Khamaganov −12 3 −1 −1 (1993). The A-factor for the reaction was estimated to be ∼1 × 10 cm molecule s . The lower limit for E/R was estimated to be > 3600 K based on the upper limit value of the rate coefﬁcient determined by Orkin and Khamaganov (1993) at 460 K. The upper limit for the rate coefﬁcient at 298 K is obtained using these parameters. References Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar, R., McKeen, S. A., Orlando, J. J., Vaghjiani, G. L. and Ravishankara, A. R.: J. Geophys. Res. 96, 5025, 1991. Orkin, V. L. and Khamaganov, V. G.: J. Atmos. Chem. 16, 169, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4450 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.253 HO + CH BrO → O + CH BrO H (1) 2 2 2 2 2 2 → O + HC(O)Br + H O (2) 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (6.7± 3.8)× 10 298 Villenave and Lesclaux, 1995 FP-UVA (a) Branching Ratios k /k ≥ 0.85 297 Chen et al., 1995 UVP-FTIR (b) k /k ≤ 0.15 Comments (a) Flash photolysis of Cl in the presence of CH Br-CH OH-O -N mixtures at a pressure of 1013 mbar. Decays in transient 2 3 3 2 2 absorptions (with contributions from CH BrO and HO ) were recorded in the wavelength range 250 nm to 280 nm. k 2 2 2 derived from simulations of the decay traces using an explicit reaction mechanism. (b) CH BrO and HO radicals were generated from the steady-state photolysis of Cl in the presence of CH Br-H -air 2 2 2 2 3 2 mixtures at 933 mbar. FTIR spectroscopic analysis identiﬁed CH BrO H and HC(O)Br as carbon-containing primary 2 2 products. The cited branching ratios were derived by taking account of secondary reactions in the system, and the possi- bility that HC(O)Br is formed from the in-situ oxidation of CH BrO H. 2 2 Preferred Values −12 3 −1 −1 k = 6.7× 10 cm molecule s at 298 K. k /k = 1.0 at 298 K. Reliability 1 log k =± 0.5 at 298 K. +0.00 1 (k /k) = at 298 K. −0.15 Comments on Preferred Values While the above value of the rate coefﬁcient seems reasonable, it has been derived from the analysis of a comparatively complex chemical system and requires independent veriﬁcation to reduce the recommended error limits. Within the uncertainty of the determination (Villenave and Lesclaux, 1995), k is indistinguishable from that recommended for the reactions of HO with CH O and CH ClO suggesting that, like Cl, the presence of the Br group has only a minor inﬂuence on the rate coefﬁcient. 3 2 2 2 However, the reported dominance of channel (1) (Chen et al., 1995) contrasts with that observed for CH ClO , for which 2 2 formation of HC(O)Cl, H O and O is the major pathway. Conﬁrmatory product studies are also required. 2 2 References Chen, J., Catoire, V. and Niki, H.: Chem. Phys. Lett. 245, 519, 1995. Villenave, E. and Lesclaux, R.: Chem. Phys. Lett. 236, 376, 1995. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4451 IV.A3.254/255 RO + NO→ RO + NO (1) 2 2 RO + NO + M→ RONO (2) 2 2 (254: R = CH Br; 255: R = CHBr ) 2 2 Rate coefﬁcient data ( k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients R=CH Br −11 (1.07± 0.11)× 10 295 Sehested et al., 1993 PR-AS (a) R=CHBr −11 (1.74± 0.16)× 10 296 Bayes et al., 2005 PLP-RF (b) Comments (a) k determined from +d [NO ]/dt at a total pressure of 1 bar. (b) Photolysis of CHBr in the presence of O and NO at 2.7–13 mbar. k was obtained from the formation kinetics of 3 2 secondary Br atoms, generated from the prompt decomposition of CHBr O. k was independent of pressure in the studied range. Preferred Values R = CH Br −11 3 −1 −1 k = 1.1× 10 cm molecule s at 298 K. 1log k =±0.3 at 298 K. R = CHBr −11 3 −1 −1 k = 1.7× 10 cm molecule s at 298 K. 1log k =±0.3 at 298 K. Comments on Preferred Values R = CH Br The preferred values are the rounded-off rate coefﬁcients determined by Sehested et al. (1993). R = CHBr The preferred value is the rounded-off rate coefﬁcient determined by Bayes et al. (2005). References Bayes, K. D., Friedl, R. R. and Sander S. P.: J. Phys. Chem., A 109, 3045, 2005. Sehested, J., Nielsen, O. J. and Wallington, T. J.: Chem. Phys. Lett., 213, 157, 1993. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4452 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.256 CH BrO + CH BrO → HC(O)Br + CH BrOH + O (1) 2 2 2 2 2 2 → CH BrO + CH BrO + O (2) 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 k = (3.26± 0.31)× 10 298 Nielsen et al., 1991 PR-UVA (a,b) obs −12 (1.05± 0.40)× 10 298 Villenave and Lesclaux, 1995 FP-UVA (c) Branching Ratios k /k ≈ 1.0 298 Nielsen et al., 1991 UVP-FTIR (d) k /k ≈ 1.0 297 Chen et al., 1995 UVP-FTIR (e) Comments (a) k is based on the measured overall second-order decay of CH BrO , deﬁned by -d[CH BrO ]/dt = 2k [CH BrO ] . obs 2 2 2 2 obs 2 2 Br atoms and HO radicals formed from the subsequent chemistry of CH BrO (formed from channel (2)) are expected to 2 2 lead to secondary removal of CH BrO , such that k represents an upper limit for the true value of k. 2 2 obs (b) Pulse radiolysis study of CH Br-O -SF mixtures with CH BrO radicals being monitored by UV absorption, with σ 3 2 6 2 2 250 nm −18 2 −1 = (7.20± 0.83)× 10 cm molecule . The derived value of k was found to be independent of wavelength over the obs range 250–310 nm and of pressure over the range 150–1000 mbar of SF . (c) Flash photolysis of Cl in the presence of CH Br-O -N mixtures at a pressure of 1013 mbar, with CH BrO radicals 2 3 2 2 2 2 −18 2 −1 being monitored by UV absorption, with σ = (3.35± 0.10)× 10 cm molecule . Decays in transient absorption 250 nm signals were recorded in the wavelength range 240 nm to 280 nm. k derived from simulations of the decay traces using an explicit reaction mechanism. (d) CH BrO radicals were generated from the steady-state photolysis of Cl in the presence of CH Br–air mixtures. Two 2 2 2 3 major carbon-containing products, CO and HC(O)Br, were observed by FTIR spectroscopic analysis. HC(O)Br was believed to arise from the reaction of CH BrO with O . 2 2 (e) CH BrO radicals were generated from the steady-state photolysis of Cl in the presence of CH Br-air mixtures at 930 2 2 2 3 mbar. FTIR spectroscopic analysis identiﬁed CH O as the major carbon-containing primary product, suggesting CH BrO 2 2 (formed from channel (2)) predominantly decomposes by Br atom elimination. Lower yields of HC(O)Br were observed, but CH BrOH was not identiﬁed as a product. CO formation also observed from secondary reactions of primary products with Cl and Br. Preferred Values k /k = 1.0 at 298 K. Reliability +0.0 1 (k /k) = at 298 K. −0.1 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4453 Comments on Preferred Values The preferred unity value of k /k is based on the results of the product study of Chen et al. (1995), in which no evidence for formation of CH BrOH (which would be formed by channel (1)) was obtained. Observation of CH O as the major primary 2 2 product was also consistent with the dominance of channel (2),followed by decomposition of CH BrO by Br atom elimination. The two kinetics studies (Nielsen et al., 1991; Villenave and Lesclaux, 1995) are in signiﬁcant disagreement, yielding rate coefﬁcients which differ by more than an order of magnitude, and UV absorption spectra for CH BrO which differ in both 2 2 shape and magnitude. The spectrum reported by Villenave and Lesclaux (1995) is similar to that typically observed for peroxy radicals, with a single maximum at 240 nm. The spectrum reported by Nielsen et al. (1991) displays a second intense maximum at 280 nm, and thus appears to be subject to interference. Although the value of k reported by Villenave and Lesclaux (1995) is likely to be indicative of the magnitude of the self- reaction rate coefﬁcient for CH BrO , the mechanism used to extract k from the observed decay proﬁles assumed secondary 2 2 removal of CH BrO by reaction with HO generated from the exclusive reaction of CH BrO with O . It is possible that the 2 2 2 2 2 actual formation of Br atoms leads to a similar degree of secondary removal of CH BrO , but Villenave and Lesclaux (1995) 2 2 did not observe formation of BrO (the likely product) in the system. More information is therefore needed on the kinetics and mechanism of the secondary reactions, in addition to further kinetics studies of the title reaction, to allow k to be deﬁned more accurately. References Chen, J., Catoire, V. and Niki, H.: Chem. Phys. Lett. 245, 519, 1995. Nielsen, O. J., Munk, J., Locke, G. and Wallington, T. J.: J. Phys. Chem. 95, 8714, 1991. Villenave, E. and Lesclaux, R.: Chem. Phys. Lett. 236, 376, 1995. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4454 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.257 BrCH CH O + BrCH CH O → BrCH CH OH + BrCH CHO + O (1) 2 2 2 2 2 2 2 2 2 2 → 2BrCH CH O + O (2) 2 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 k = (6.2± 1.2)× 10 298 Crowley and Moortgat, 1992 MM-UVA (a,b) obs −14 6.15× 10 exp[(1247± 203)/T ] 275-373 Villenave et al., 2003 FP-UVA (c) −12 (4.49± 0.22)× 10 298 Branching Ratios k /k = 0.43 296 Yarwood et al., 1992 UV-P-FTIR (d) k /k = 0.57 Comments (a) k is based on the measured overall second-order decay of CH BrCH O , deﬁned by -d[CH BrCH O ]/dt = 2k obs 2 2 2 2 2 2 obs [CH BrCH O ] . As described in detail by Lesclaux (1997), HO radicals formed from the subsequent chemistry of 2 2 2 2 CH BrCH O (formed from channel (2)) are expected to lead to secondary removal of CH BrCH O . The true value of k 2 2 2 2 2 is expected to fall in the range k /(1 + α) < k < k , where α = k /k. obs obs 2 (b) Molecular modulation study of the photolysis of Br in the presence of C H -O -N mixtures at total pressures up to 800 2 2 4 2 2 mbar. Modulated waveforms for the formation and removal of CH BrCH O radicals were monitored by absorption at 2 2 2 270 nm, i.e. where HO does not absorb. (c) Flash photolysis of Br in the presence of C H -O -N mixtures at a pressure of 1013 mbar. Decays in transient absorption 2 2 4 2 2 signals (with contributions from CH BrCH O and HO ) were recorded in the wavelength range 210 nm to 290 nm. k 2 2 2 2 derived from simulations of the decay traces using an explicit reaction mechanism. (d) Steady-state photolysis of Br in the presence of C H -O -N mixtures at 933 mbar total pressure, with FTIR spectro- 2 2 4 2 2 scopic determination of products. The major products observed were BrCH CHO, BrCH CH OH, and BrCH CH OOH. 2 2 2 2 2 The branching ratio, k /k = 1.35± 0.07, was determined from the yields of BrCH CHO and BrCH CH OH relative to 2 1 2 2 2 the loss of C H . 2 4 Preferred Values −12 3 −1 −1 k = 4.0× 10 cm molecule s at 298 K. −14 3 −1 −1 k = 6.0× 10 exp(1250/T ) cm molecule s over the temperature range 270-380 K. k /k = 0.43 at 298 K. k /k = 0.57 at 298 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 500 K. 1 (k /k) = (k /k) =±0.1 at 298 K. 1 2 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4455 Comments on Preferred Values The preferred values of k are based on the temperature dependence expression of Villenave et al. (2003), with which the earlier 298 K k determination of Crowley and Moortgat (1992) is entirely consistent. The preferred values of the branching ratios obs are based on the data of Yarwood et al. (1992), which require conﬁrmation. The above value of k is similar to that for the self-reaction of CH ClCH O , both showing an enhancement of a factor of ca. 2 2 2 50 compared with the self-reaction rate coefﬁcient for the unsubstituted analogue, C H O . 2 5 2 References Crowley, J. N. and Moortgat, G. K.: J. Chem. Soc. Faraday Trans. 88, 2437, 1992. Lesclaux, R.: Combination of peroxyl radicals in the gas phase. In ’Peroxyl Radicals’, edited by Alfassi, Z. B., John Wiley and Sons, 1997. Villenave, E., Moisan, S. and Lesclaux, R.: J. Phys. Chem. A 107, 2470, 2003. Yarwood, G., Peng, N. and Niki, H.: Int. J. Chem. Kinet. 24, 369, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4456 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.258 BrO + CH O → CH O + BrOO (1) 3 2 3 → CH O + OBrO (2) → HOBr + CH O (3) 2 2 ◦ −1 1H (1) = -3.5 kJ·mol ◦ −1 1H (2)= +52.4 kJ·mol Rate coefﬁcient data (k = k + k + k ) 1 2 3 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 (5.7± 0.6)× 10 298 Aranda et al., 1997 DF-MS/LIF (a) Branching Ratios k /k = 0.8± 0.2 298 Aranda et al., 1997 DF-MS/LIF (a) (k + k )/k = 0.3± 0.1 298 1 2 Comments (a) Flow tube operated at 1.3 mbar of He. BrO and CH O were formed in the reactions Br + O , and F + CH in the presence 3 2 3 4 of O , respectively, and monitored by MS as their parent ions. The experiments were conducted under pseudo ﬁrst-order conditions, with BrO in excess of CH O . The products observed were HOBr (MS) and CH O (LIF). The CH O proﬁle 3 2 3 3 was modeled by taking into account its presence as impurity in the CH O source, and its reaction with BrO. 3 2 Preferred Values −12 3 −1 −1 k = 5.7× 10 cm molecule s at 298 K. k /k = 0.25 at 298 K. k /k = 0.75 at 298 K. Reliability 1 log k =± 0.3 at 298 K. 1 (k /k) =± 0.2 at 298 K. +0.25 1 (k /k) = at 298 K. −0.4 Comments on Preferred Values The preferred value of k(298 K) is taken from the sole study of this reaction with expanded error limits. The branching ratio to HOBr formation (reaction 3) was determined as (0.8 ± 0.2), and that to CH O formation as (0.3 ± 0.1). Since this study, it has been shown that OBrO has a stable positive ion under similar experimental conditions (Li, 1999), and would have been observed by these authors if it were a signiﬁcant product. They also report non-observation of CH OBr and HBr. We also note that channel (2) is signiﬁcantly endothermic, whilst channel (3) is, within error limits, thermoneutral (Aranda et al., 1997). For this reason we do not consider reaction (2) and prefer to quote k /k = 0.25 and k /k = 0.75. We add expanded error limits to 1 3 reﬂect the fact that calibration of the CH O signal was achieved by modeling the CH O source chemistry, which contains 3 3 2 signiﬁcant uncertainty, and because HOBr was not directly calibrated. In the study of Aranda et al. (1997) it is not clear how the direct formation of HOBr in channel (3) was separated from the indirect formation via channel (1) followed by rapid reaction of CH O with the excess BrO (Aranda et al., 1998). Theoretical studies (Guha and Francisco, 2003) have been unable to reproduce the experimentally derived reaction mechanism and suggest that HOOBr and HCHO are formed via rearrangement of a CH OOOBr association complex. Further experiments to examine temperature dependent kinetics and product formation in this reaction are desirable. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4457 References Aranda, A., Le Bras, G., La Verdet, G. and Poulet, G.: Geophys. Res. Lett. 24, 2745, 1997. Aranda, A., Daele, ¨ V., Le Bras, G. and Poulet, G.: Int. J. Chem. Kinetic. 30, 249, 1998. Guha, S. and Francisco, J. S.: J. Chem. Phys. 118, 1779, 2003. Li, Z.: J. Phys. Chem. A. 103, 1206, 1999. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4458 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.259 CH Br + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CH Br + hν → CH + Br 296 404 3 3 Absorption cross-section data Wavelength range/nm Reference Comments 180–260 Gillotay and Simon, 1988 (a) Quantum yield data Measurement Wavelength range/nm Reference Comments 8(Br)=1.01± 0.16 248 Talukdar et al., 1992 (b) 8(Br)=1.10± 0.20 222 8(Br)=1.05± 0.11 193 8(H)=0.002± 0.001 193 Comments (a) Spectra were obtained using a thermostatted absorption cell with a single pass optical path of 2 m coupled to a monochro- mator capable of a maximum resolution of 0.015 nm. Pressures of CH Br used covered the range 0.053 - 29 mbar. Spectra were recorded at 295 K, 270 K, 250 K, 230 K and 210 K. The data were ﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. (b) Pulsed laser photolysis of CH Br-N or He mixtures and detection of Br( P ) by resonance ﬂuorescence. A small 3 2 3/2 2 2 amount of H was added to ensure rapid quenching of the Br( P ) also produced. The Br( P ) measurements were 2 1/2 3/2 calibrated by HBr photolysis at 193 nm for which a quantum yield of unity was assumed. No H atom production could be detected in the 248 nm and 222 nm photolyses. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4459 Preferred Values Absorption cross-sections of CH Br at 295 K and 210 K. 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 190 43.9 (a) 226 23.0 21.6 192 52.9 (a) 228 18.8 17.7 194 62.0 (a) 230 15.4 14.4 196 69.1 (a) 232 12.4 11.4 198 76.0 (a) 234 9.87 8.86 200 79.1 (a) 236 7.65 6.58 202 79.7 (a) 238 5.95 4.97 204 79.3 (a) 240 4.47 3.79 206 76.7 (a) 242 3.35 2.76 208 72.7 (a) 244 2.50 1.94 210 66.6 (a) 246 1.82 1.42 212 61.4 61.3 248 1.31 0.980 214 55.9 55.6 250 0.957 0.675 216 49.3 49.0 252 0.686 0.447 218 44.2 43.3 254 0.487 0.315 220 37.7 36.6 256 0.336 0.202 222 32.4 31.2 258 0.235 0.129 224 27.6 25.9 260 0.164 0.088 (a) No detectable change in σ over the range 210–295 K Quantum Yield 8 = 1.0 over the wavelength range 200–260 nm. Comments on Preferred Values The preferred values of the absorption cross-section at 295 K and 210 K are those reported by Gillotay and Simon (1988). Values have also been reported at 298 K by Molina et al. (1982) at 5 nm intervals and by Robbins (1976), at 2 nm intervals. The agreement among these three studies is very good. Gillotay and Simon (1988) have ﬁtted their data to a polynomial to give an expression for the cross sections as a function of temperature and pressure. The preferred values for the quantum yield are based on the study of Talukdar et al. (1992) who showed that photolysis occurs with unit quantum efﬁciency by rupture of the C-Br bond. References Gillotay, D. and Simon, P. C.: Annal. Geophys. 6, 211, 1988. Molina, L. T., Molina, M. J. and Rowland, F. S.: J. Phys. Chem. 86, 2672, 1982. Robbins, D. E.: Geophys. Res. Lett. 3, 213, 1976. Talukdar, R. K., Vaghjiani, G. L. and Ravishankara, A. R.: J. Chem. Phys. 96, 8194, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4460 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.260 CF Br + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CF Br + hν → CF + Br 296 404 3 3 Absorption cross-section data Wavelength range/nm Reference Comments 168–280 Gillotay and Simon, 1989 (a) 190-285 Burkholder et al., 1991 (b) 190-320 Orkin and Kasimovskaya, 1995 (c) Quantum yield data Measurement Wavelength range/nm Reference Comments 1.12± 0.16 193 Talukdar et al., 1992 (d) 0.92± 0.15 222 Comments (a) Spectra were obtained using a thermostatted absorption cell with a single pass optical path of 2 m coupled to a monochro- mator capable of a maximum resolution of 0.015 nm. Pressures of CF Br used covered the range 0.8–950 mbar. Spectra were recorded at 295 K, 270 K, 250 K, 230 K and 210 K. The data were ﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. (b) Spectra were obtained using thermostatted absorption cells with single pass optical paths of 98.1 cm and 150 cm, coupled to spectrographs having resolutions in the range 0.4–0.5 nm. Spectra were recorded at 296 K, 270 K, 250 K, 230 K and 210 K. The data wereﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. (c) Spectra were obtained using a cell thermostatted at 295 K with a single path optical length of 14.0 cm and coupled to a double beam spectrophotometric system. Sample pressures in the range 0.013–1 bar were used. (d) Pulsed laser photolysis of CF Br-N mixtures and detection of Br( P ) by resonance ﬂuorescence. A small amount of 3 2 3/2 2 2 H was added to ensure rapid quenching of the Br( P ) also produced. The Br( P ) measurements were calibrated by 2 1/2 3/2 CH Br photolysis at the same wavelength for which a quantum yield of unity was assumed. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4461 Preferred Values Absorption cross-sections of CF Br at 295 K and 210 K. 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 190 6.50 7.11 230 2.98 2.24 192 7.49 8.27 232 2.35 1.67 194 8.49 9.43 234 1.83 1.21 196 9.48 10.6 236 1.40 0.863 198 10.4 11.7 238 1.06 0.607 200 11.2 12.6 240 0.789 0.420 202 11.8 13.2 242 0.574 0.287 204 12.2 13.6 244 0.418 0.193 206 12.4 13.8 246 0.301 0.129 208 12.3 13.6 248 0.216 0.0848 210 12.0 12.9 250 0.153 0.0562 212 11.3 12.1 252 0.107 0.0371 214 10.6 11.1 254 0.0751 0.0241 216 9.69 9.86 256 0.0524 0.0163 218 8.65 8.54 258 0.0364 0.0110 220 7.58 7.25 260 0.0252 0.0074 222 6.52 5.97 262 0.0176 224 5.50 4.84 264 0.0121 226 4.56 3.86 266 0.0086 228 3.73 2.96 268 0.0061 Quantum Yields 8 = 1.0 over the wavelength range 200–270 nm. Comments on Preferred Values The preferred values of the absorption cross-sections at 295 K are the mean of the values obtained in the studies of Gillotay and Simon (1989), Burkholder et al. (1991) and Orkin and Kasimovskaya (1995). Molina et al. (1982) have also reported values at 5 nm intervals. The agreement among these four studies (Gillotay and Simon, 1989; Burkholder et al., 1991 and Orkin and Kasimovskaya, 1995) over the wavelength range of the preferred values is excellent. The temperature dependence of the of the cross sections down to 210 K has been studied by Gillotay and Simon (1989) and by Burkholder et al. (1991) and in both cases polynomial expressions were derived giving the cross sections as a function of temperature and wavelength. There are signiﬁcant differences between the two studies (Gillotay and Simon, 1989; Burkholder et al., 1991). Thus at λ > 220 nm both studies reported a decrease in absorption as the temperature was lowered, but near the absorption peak (∼ 205 nm) Burkholder et al. (1991) found the cross-sections to be independent of temperature, while Gillotay and Simon (1989) found the absorption to increase with decreasing temperature, with a 20% increase at the lowest temperature studied. Furthermore, at 210 K there is good agreement on the values of σ at longer wavelengths (∼ 280 nm), but the discrepancy between the two studies (Gillotay and Simon, 1989; Burkholder et al., 1991) increases steadily in going to shorter wavelengths with the values of Gillotay and Simon (1989) being∼30% larger than those of Burkholder et al. (1991) at 190 nm. Provisionally, the preferred values at 210 K are taken as the mean of the values of Gillotay and Simon (1989) and of Burkholder et al. (1991). The preferred quantum yields are based on the study of Talukdar et al. (1992) in which it was shown that photolysis occurs with unit quantum efﬁciency by rupture of the C-Br bond to give CF + Br. Studies of the dynamics of photodissociation at 234 nm show that 80% of the Br atoms are produced in the P excited state (Kim et al., 2001). CF Br has no apparent 1/2 3 tropospheric chemistry loss mechanism (Burkholder et al., 1991) and is estimated to have a tropospheric lifetime with respect to photolysis of greater than 1000 years (Molina et al., 1982). www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4462 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar, R., McKeen, S. A., Orlando, J. J., Vaghjiani, G. L. and Ravishankara, A. R.: J. Geophys. Res. 96, 5025, 1991. Gillotay, D. and Simon, P. C.: J. Atmos. Chem. 8, 41, 1989. Kim, T. K., Park, M. S., Lee, K. W. and Jung, K-H.: J. Chem. Phys., 115, 10745, 2001. Molina, L. T., Molina, M. J. and Rowland, F. S.: J. Phys. Chem. 86 2672, 1982. Orkin, V. L. and Kasimovskaya, E. E.: J. Atmos. Chem. 21, 1, 1995. Talukdar, R. K., Vaghjiani, G. L. and Ravishankara, A. R.: J. Chem. Phys. 96, 8194, 1992. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4463 IV.A3.261 CF ClBr + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CF ClBr + hν → CF + ClBr (1) 296 445 2 2 → CF Cl + Br (2) 271 441 → CF Br + Cl (3) 348 (est) 344 → CF + Cl+ Br (4) 488 245 Absorption cross-section data Wavelength range/nm Reference Comments 170–302 Gillotay and Simon, 1989 (a) 190–320 Burkholder et al., 1991 (b) 190–304 Orkin and Kasimovskaya, 1995 (c) Quantum yield data Measurement Wavelength range/nm Reference Comments 8(Cl) = 1.03± 0.14 193 Talukdar et al., 1996 (d) 8(Br) = 1.04± 0.14 193 8(CF ) = 0.9± 0.2 193 8(Cl) = 0.27± 0.04 222 8(Br) = 0.86± 0.04 222 8(Cl) = 0.18± 0.03 248 8(Br) = 0.75± 0.12 248 8(3) = 0.29± 0.03 157.6 Yokoyama et al., 2001 (e) 8(2) = 0.46± 0.05 157.6 8(4) = 0.25± 0.05 157.6 8(3) = 0.24 234 Lee and Yung, 2001 (f) 8(2) = 0.96 234 Comments (a) Spectra were obtained using a thermostatted absorption cell with a single pass optical path of 2 m coupled to a monochro- mator capable of a maximum resolution of 0.015 nm. Pressures of CF ClBr used covered the range 0.13 – 600 mbar. Spectra were recorded at 295 K, 270 K, 250 K, 230 K and 210 K. The data were ﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. (b) Spectra were obtained using thermostatted absorption cells with single pass optical paths of 98.1 cm and 150 cm, coupled to spectrographs having resolutions in the range 0.4–0.5 nm. Spectra were recorded at 296 K, 270 K, 250 K, 230 K and 210 K. The data were ﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. (c) Spectra were obtained using a cell thermostatted at 295 K with a single path optical length of 14.0 cm and coupled to a double beam spectrophotometric system. Sample pressures in the range 0.013–1 bar were used. (d) Quantum yields were determined by photolysis of CF ClBr and a reference compound in ”back-to-back” experiments. For 8(Cl) determinations at 193 nm the reference compound was HCl and at 222 nm and 248 nm Cl atom yields were www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4464 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry measured relative to those at 193nm. CH Br and C F were used as reference compounds for measuring the yields of Br 3 2 4 and CF respectively. [Cl] and [Br] were monitored by RF and [CF ] by long path absorption. [CF ClBr] and [HCl] were 2 2 2 determined by UV absorption and [C F ] by pressure measurements. 2 4 (e) Laser photolysis with photofragment translational spectroscopy using TOF-MS to detect Br, Cl and CF . All CClF and 2 2 CBrF radicals produced dissociate spontaneously to produce Cl or Br + CF . 2 2 (f) Laser photolysis with state selected photofragment imaging. Two primary channels (2) and (3) observed with relative 2 2 yields of 0.96 and 0.04. For the CF Cl + Br channel the branching ratio for Br( P ) and Br( P ) is determined to be 2 1/2 3/2 0.41±0.05. Preferred Values Absorption cross-sections of CF ClBr at 295 K and 210 K. 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 190 47.4 50.5 240 17.7 15.6 192 57.7 64.5 242 14.5 12.6 194 70.3 79.3 244 11.9 9.97 196 83.0 94.3 246 9.66 7.82 198 95.6 106 248 7.77 6.13 200 109 120 250 6.23 4.70 202 117 130 252 4.93 3.57 204 121 132 254 3.89 2.72 206 122 134 256 3.05 2.02 208 121 133 258 2.37 1.51 210 117 129 260 1.83 1.11 212 112 123 262 1.41 0.811 214 104 115 264 1.07 0.589 216 96.2 106 266 0.816 0.425 218 87.8 96.2 268 0.618 0.307 220 79.0 86.0 270 0.465 0.216 222 70.3 75.7 272 0.349 0.153 224 62.1 66.2 274 0.259 0.107 226 54.3 57.2 276 0.190 0.0742 228 47.3 49.0 278 0.139 0.0516 230 40.9 41.3 280 0.103 0.0355 232 35.2 34.6 282 0.075 0.0244 234 29.9 28.8 284 0.055 0.0167 236 25.4 23.7 286 0.040 0.0106 238 21.3 19.4 288 0.029 0.00721 Quantum Yields 8 = 1.0 over the wavelength range 200–300 nm. Comments on Preferred Values The preferred values of the absorption cross-sections at 295 K are the mean of the values obtained in the studies of Gillotay and Simon (1989), Burkholder et al. (1991) and Orkin and Kasimovskaya (1995). Values have also been reported by Molina et al. (1982) at 5 nm intervals, and by Giolando et al. (1980) at 10 nm intervals. The agreement among these ﬁve studies (Gillotay and Simon, 1989: Burkholder et al., 1991; Orkin and Kasimovskaya, 1995; Molina et al., 1982; Giolando et al., 1980) at 295 K Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4465 over the wavelength range of the preferred values is excellent. The temperature dependence of the cross-sections down to 210 K has been studied by Gillotay and Simon (1989) and by Burkholder et al. (1991) and in both cases polynomial expressions were derived giving the cross-sections as a function of temperature and wavelength. At λ > 234 nm both studies reported a decrease in absorption as the temperature was lowered. But near the absorption peak (∼ 205 nm) Burkholder et al. (1991) found the cross-sections to be independent of temperature, while Gillotay and Simon (1989) found the absorption to increase with decreasing temperature, with a 20% increase at the lowest temperature studied. Furthermore, at 210 K the values of σ of Gillotay and Simon (1989) are larger than those of Burkholder et al. (1991) by ∼ 13% at 288 nm, increasing to ∼ 30% at 190 nm. Provisionally, the preferred values at 210 K are taken as the mean of the values from Gillotay and Simon (1989) and Burkholder et al. (1991). Talukdar et al. (1996) measured the quantum yields of CF , Cl, and Br at 193 nm and found that the CF ClBr was pho- 2 2 todissociated to give CF with a quantum yield of unity, probably by initial production of CF Cl which was not collisionally 2 2 stabilized under their conditions but went on to give CF + Cl. Baum and Huber (1993), in a photofragment translational spec- troscopy study, also found that at 193 nm the dominant primary process is rupture of the C-Br bond followed by decomposition of the energised CF Cl fragment, and a minor pathway involving initial rupture of the C-Cl bond was also detected. At 157.6 nm CF ClBr dissociates competitively in all three dissociation channels (2), (3 and (4), with 25% producing CF directly via 2 2 (4) (Yokoyama et al., 2001). At longer wavelengths photodissociation by breaking of a C-halogen bond is expected to persist with unit quantum efﬁciency, with direct Cl production (channel 3) decreasing to near zero at 267 nm (Huang et al., 2003). CF ClBr has been estimated to have a tropospheric lifetime with respect to photolysis of 15 to 20 years (Burkholder et al., 1991; Molina et al., 1982). References Baum, G. and Huber, J. R.: Chem. Phys. Lett. 213, 427, 1993. Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar, R., McKeen, S. A., Orlando, J. J., Vaghjiani, G. L. and Ravishankara, A. R.: J. Geophys. Res. 96, 5025, 1991. Gillotay, D. and Simon, P. C.: J. Atmos. Chem. 8, 41, 1989. Giolando, D. M., Fazekas, G. B., Taylor, W. D. and Takacs, G. A.: J. Photochem. 14, 335, 1980. Huang, J., Dadong, X., Francisco, J. S. and Jackson, W. M.: J. Chem. Phys., 119, 3661, 2003. Lee, S-H. and Yung, K-H.: Chem. Phys. Lett., 350, 306 , 2001. Molina, L. T., Molina, M. J. and Rowland, F. S.: J. Phys. Chem. 86 2672, 1982. Orkin, V. L. and Kasimovskaya, E. E.: J. Atmos. Chem. 21, 1, 1995. Talukdar, R. K., Hunter, M., Warren, R. F., Burkholder, J. B. and Ravishankara, A. R.: Chem. Phys. Lett. 262, 669, 1996. Yokoyama, A., Yokoyama, K. and Takayanagi, T.: J. Chem. Phys., 114, 1617, 2001. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4466 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A3.262 CF Br + hν → products 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CF Br + hν → CF Br + Br (1) 280 (est) 427 2 2 2 → CF + Br + Br (2) 419 286 → CF + Br (3) 226 529 2 2 Absorption cross-section data Wavelength range/nm Reference Comments 170–302 Gillotay and Simon, 1989 (a) 190–320 Burkholder et al., 1991 (b) 190–304 Orkin and Kasimovskaya, 1995 (c) Quantum yield data Measurement Wavelength range/nm Reference Comments 8(CF O) = 1.14 206.2 Molina and Molina, 1983 (d) 8(Br ) = 1.11 8(-CBr F ) = 1.12 2 2 8(CF ) = 1.03 247.7 8(Br ) = 0.99 8(-CBr F ) = 1.05 302.4 2 2 8(CF O) = 1.23 8(Br ) = 1.28 8(Br) = 1.96± 0.25 193 Talukdar et al., 1992 (e) 8(Br) = 1.63± 0.19 222 8(Br) = 1.01± 0.15 248 8(CF ) = 1.11± 0.22 193 Talukdar et al., 1996 (e) 8(CF ) = 1.18± 0.30 193 8(1) = 0.84 234 Park et al., 2001 (f) 8(2) = 0.15 8(3) = trace 8(3) = 0.04± 0.01 248 Hsu et al., 2005 (g) Comments (a) Spectra were obtained using a thermostatted absorption cell with a single pass optical path of 2 m coupled to a monochro- mator capable of a maximum resolution of 0.015 nm. Pressures of CF Br used covered the range 0.04–308 mbar. Spectra 2 2 were recorded at 295 K, 270 K, 250 K, 230 K and 210 K. The data were ﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. (b) Spectra were obtained using thermostatted absorption cells with single pass optical paths of 98.1 cm and 150 cm, coupled to spectrographs having resolutions in the range 0.4–0.5 nm. Spectra were recorded at 296 K, 270 K, 250 K, 230 K and 210 K. The data were ﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4467 (c) Spectra were obtained using a cell thermostatted at 295 K with a single path optical length of 14.0 cm and coupled to a double beam spectrophotometric system. Sample pressures in the range 0.013–1 bar were used. (d) Product study on photolysis of CF Br -air mixtures at 1 bar. The only photolysis products found were CF O and Br . 2 2 2 2 The CF O and CBr F concentrations were monitored by FTIR, and the Br concentrations by UV absorption. 2 2 2 2 (e) Both of the studies of Talukdar et al. (1992; 1996) employed basically the same technique. Pulsed laser photolysis of ﬂowing CF Br -diluent (He, N , or Ar) mixtures was used with a small amount of H added to ensure rapid quenching 2 2 2 2 2 2 2 of the Br( P ) produced to Br( P ). Br( P ) was detected by resonance ﬂuorescence and CF by UV absorption. 1/2 3/2 3/2 2 The two values of 8(CF ) cited were obtained by monitoring [CF ] at 248.7 and 258.3 nm. The Br( P ) measurements 2 2 3/2 were calibrated by CH Br photolysis at the same wavelength for which a quantum yield of unity was assumed. The CF 3 2 measurements were calibrated using C F photolysis taking a quantum yield for CF production at 193 nm of 2. 2 4 2 (f) Photodissociation dynamics of CF Br studied using 2-dimensional photofragment ion image technique, following laser 2 2 photolysis at 234 and 265 nm. At 265 nm the radical channel (1) is the major primary dissociation channel. 3 1 (g) Laser photolysis at 248 nm with CRDS detection of nascent Br in the B 5+ - X 6+ transition. 2 u g Preferred Values Absorption cross-sections of CF Br at 295 K and 210 K. 2 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 190 117 130 250 58.3 55.3 192 110 122 252 46.5 39.1 194 102 110 254 36.8 29.9 196 91.4 97.8 256 28.9 22.6 198 82.1 86.3 258 22.4 17.0 200 74.8 78.4 260 17.3 12.5 202 71.7 74.5 262 13.1 9.17 204 73.4 77.1 264 9.90 6.66 206 80.9 85.2 266 7.47 4.81 208 92.3 100 268 5.59 3.44 210 110 120 270 4.17 2.44 212 134 145 272 3.08 1.72 214 155 173 274 2.27 1.21 216 180 202 276 1.66 0.844 218 205 230 278 1.21 0.588 220 226 254 280 0.888 0.406 222 244 273 282 0.647 0.281 224 253 282 284 0.470 0.194 226 257 283 286 0.336 0.129 228 253 277 288 0.245 0.0891 230 245 264 290 0.177 0.0616 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4468 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 232 230 245 292 0.128 0.405 234 212 222 294 0.093 0.277 236 192 197 296 0.067 0.185 238 170 171 298 0.049 0.127 240 147 145 300 0.035 0.0083 242 126 121 302 0.025 0.0056 244 106 99.3 304 0.018 0.0011 246 87.8 86.4 306 0.013 248 72.0 64.1 308 0.009 Quantum Yields 8 = (8 + 8 + 8 ) = 1.0 over the range 200–310 nm. 1 2 3 Comments on Preferred Values The preferred values for the absorption cross-sections at 295 K are the means of the values reported by Gillotay and Simon (1989), Burkholder et al. (1991) and Orkin and Kasimovskaya (1995). Values at 5 nm intervals have also been reported by Molina et al. (1982). The agreement among the four studies (Gillotay and Simon, 1989; Burkholder et al., 1991; Orkin and Kasimovskaya, 1995; Molina et al.,1982) over the wavelength range of the preferred values is very good although discrepancies appear at longer wavelengths. The temperature dependence down to 210 K has been studied by Gillotay and Simon (1989) and Burkholder et al. (1991). There is only fair agreement between the two studies. At λ > 250 nm both report a decrease in absorption as the temperature is lowered (Gillotay and Simon, 1989; Burkholder et al., 1991), and near the absorption peak (about 230 nm) both studies ﬁnd an 11% increase in absorption in going to the lowest temperature. However, although the values of σ from the two studies are in good agreement close to the absorption maximum they steadily diverge on moving to longer and shorter wavelengths reaching a 30% difference at 190 nm and a factor of 2 at 300 nm. Provisionally, the preferred values at 210 K are taken as the mean of the values from Gillotay and Simon (1989) and Burkholder et al. (1991). Molina and Molina (1983) found that the only products of photolysis of CF Br -air mixtures at a pressure of 1 bar were 2 2 CF O and Br and concluded that the quantum yield for photodissociation of CBr F was unity over the wavelength range 2 2 2 2 200–300 nm. This is supported by the ﬁndings of Talukdar et al. (1992; 1996). The preferred values for the quantum yields are based on the studies of Molina and Molina (1983) and Talukdar et al. (1992; 1996). Molecular beam (Krajnovich et al., 1984) and spectroscopic studies (Gosnell et al., 1991; Vatsa et al., 1995) at 248 nm have detected the transient CF Br. Cameron et al. (2000) used LIF to detect vibrational distribution of nascent CF produced by photolysis of CBr F at discrete wavelegths 2 2 2 in the range 223–260 nm. Their results showed that CF production at 246 nm was accompanied by the production of two Br fragments. However Hsu et al (2005) measured signiﬁcant Br production (φ = 0.04) at 248 nm using CRDS detection, and Park et al (2001) report seeing a Br elimination channel at 234 nm. Here is insufﬁcient information to recommend λ dependence of φ(Br), but it is recommended to use φ(Br) = 1.0 for tropospheric photolysis and φ(Br) = 2.0 for stratospheric photolysis. Because its absorption extends into the 290–310 nm wavelength range, CF Br has a short tropospheric lifetime with respect 2 2 to photolysis, of about 3 years. References Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar,R., McKeen, S. A., Orlando, J. J., Vaghjiana, G. L. and Ravishankara, A. R.: J. Geophys. Res. 96, 5025, 1991. Cameron, M. R., Johns, S. A., Metha, G. F. and Cable, S.F.: Phys. Chem. Chem. Phys., 2, 2539. 2000. Gillotay, D. and Simon, P.C.: J. Atmos. Chem., 8, 41, 1989. Gosnell, T. R., Taylor, A. J. and Lyman, J. L.: J. Chem. Phys., 94, 5949, 1991. Hsu, C-Y., Huang, H-Y. and Lin, K-C.: J. Chem. Phys., 123, 134312, 2005. Krajnovich, D., Zhang, Z., Butler, L. and Lee, Y. T.: J. Phys. Chem., 88, 4561,1984. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4469 Orkin, V. L. and Kasimovskaya, E. E.: J. Atmos. Chem., 21, 1, 1995. Molina, L. T., Molina, M. J. and Rowland, F. S.: J. Phys. Chem., 86, 2672, 1982. Molina, L. T. and Molina, M. J.: J. Phys. Chem., 87, 1306, 1983. Park, M. S., Kim, T. K., Lee, S-H. and Jung, K-H., Vollp, H-R. and Wolfrum, J.: J. Phys. Chem., 105, 5606, 2001. Talukdar, R. K., Vaghjiani, G. L. and Ravishankara, A. R.: J. Chem. Phys., 96, 8194, 1992. Talukdar, R. K., Hunter, M., Warren, R. F., Burkholder, J. B. and Ravishankara, A. R.: Chem. Phys. Lett., 262, 669, 1996. Vatsa, R. K., Kumar, A., Naik, P. D., Rao, K. V. S. R. and Mittal, J. P.: Bull. Chem. Soc. Jpn., 68, 2817, 1995 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4470 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A4.263 CHBr + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CHBr + hν → CHBr + Br (1) 276 433 3 2 → CHBr +Br (2) 355 337 Absorption cross-section data Wavelength range/nm Reference Comments 170–310 Gillotay and Simon, 1989 (a) 286–362 Moortgat et al., 1993 (b) Quantum yield data Measurement Wavelength range/nm Reference Comments 8(Br) = 0.74 234 Xu et al., 2002 (c) 8(Br ) = 0.26 8(Br) = 0.84 267 8(Br ) = 0.16 8(Br) = 1.0 302-306 Bayes et al., 2003 (d) 8(Br) = 0.76± 0.03 266 8(Br ) = 0.23± 0.05 248 Huang et al., 2004 (e) Comments (a) Two different techniques were used. One employed a cell with a ﬁxed optical path of 2 m and an evacuated monochromator capable of reaching wavelengths down to 170 nm. In the other a multiple reﬂection cell with optical paths up to 5 m was used. In both cases the cells were thermostatted and measurements were made in the range 295–240 K. (b) Measurements were made using two pieces of apparatus. In one a cell of 63 cm ﬁxed path length was used and measure- ments made at 296 K. The other contained multiple pass optics with a total path length of 980 cm. The latter system was used for measurements at 296 K, 286 K, 266 K, and 256 K. (c) Photodissociation dynamics of CHBr studied using photofragment TOF-MS and velocity ion image imaging, following 2 2 laser photolysis at 234 and 265 nm. Both excited spin orbit excited Br( P ) and ground Br( P ) were found by REMPI, 1/2 3/2 and VUV photoionisation at 118 nm to detect radical products. (d) Photolysis of using PLP with joule meter to measure the average pulse energy. Br detected by VUV-RF at discrete λ between 130–163 nm. 3 1 (e) Laser photolysis at 248 nm with CRDS detection of nascent Br in the B 5+ - X 6+ transition. 2 u g Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4471 Preferred Values Absorption cross-sections of CHBr at 296 K and 210 K. 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 190 399 393 270 30.8 21.1 192 360 351 272 24.8 16.5 194 351 353 274 19.8 12.8 196 366 383 276 15.8 9.94 198 393 422 278 12.5 7.66 200 416 466 280 9.88 5.88 202 433 475 282 7.77 4.50 204 440 474 284 6.10 3.42 206 445 467 286 4.81 2.60 208 451 471 288 3.75 1.97 210 468 490 290 2.88 1.49 212 493 522 292 2.22 1.05 214 524 551 294 1.70 0.757 216 553 593 296 1.28 0.547 218 574 621 298 0.951 0.395 220 582 633 300 0.719 0.285 222 578 623 302 0.530 0.206 224 558 597 304 0.394 0.149 226 527 562 306 0.298 0.107 228 487 516 308 0.226 0.078 230 441 465 310 0.171 0.060 232 397 409 312 0.127 0.040 234 362 362 314 0.095 0.029 236 324 324 316 0.071 0.021 238 295 295 318 0.053 0.015 240 273 272 320 0.039 0.011 242 253 250 322 0.029 0.0079 244 234 224 324 0.021 0.0057 246 214 202 326 0.016 0.0041 248 194 178 328 0.009 0.0030 250 174 157 330 0.009 0.0022 252 158 138 332 0.007 0.0016 254 136 116 334 0.005 0.0011 256 116 96.2 336 0.004 0.00081 258 98.6 79.5 338 0.003 0.00059 260 82.8 64.7 340 0.002 0.00042 262 68.9 52.5 264 56.9 42.2 266 46.7 33.7 268 38.0 26.7 Comments on Preferred Values There have been two studies of the absorption cross-sections of CHBr . Gillotay et al. (1989) reported values over the wavelength range 170–310 nm and the temperature range 295–240 K; Moortgat et al. (1993) reported values over the range 245–360 nm and the temperature range 296–256 K. In the region where the measurements overlap, the agreement is very good. The preferred values at 296 K are those reported by Gillotay et al. (1989) over the wavelength range 190–284 nm and those www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4472 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry reported by Moortgat et al. (1993) at longer wavelengths. The preferred values at 210 K are those of Gillotay et al. (1989) over the range 190–298 K, which they obtained by extrapolation of their higher temperature results, and those over the range 290–340 K are from the expression, ln σ (λ,T ) = (0.0618350 - 0.000241014 λ)(273-T ) - (2.37616 + 0.1475688 λ), which was derived by Moortgat et al. (1993) from a ﬁt to the combined data of their study and that of Gillotay et al. (1989). It is valid in the wavelength range 290–340 nm and the temperature range 300–210 K. The quantum yield for the formation of Br atoms determined by Bayes et al. (2003) for 303 to 306 nm, the Br-atom quantum yield was unity within experimental error. At longer wavelengths, the quantum yields decreases to 0.76 at 324 nm, but the authors claim that the lower than unity values are the result of systematic and random errors and/or incorrect absorption cross sections. Support for unity quantum yield at λ >300 nm comes from theoretical calculations by Peterson and Francisco (2002), and is recommended for modeling in the troposphere. Bayes et al. (2003) also report a Br-atom quantum yield of 0.76± 0.03 at 266 nm, indicating that another photodissociation channel becomes important. This conﬁrms the result of Xu et al. (2002) who measured atomic Br and molecular Br by TOF mass spectrometry from bromoform photolysis at 234 and 267 nm. Huang (2004) also observed Br production at 248 nm, using CRDS to probe the molecular fragment, and measured a quantum yield of 0.23±0.05. On the other hand the experiments of McGivern et al. (2000) and Zou et al. (2004), using VUV ionisation photofragment translational spectroscopy at 193 nm and at 248 nm respectively, suggest that Br fragments do not arise from a single photon channel, and that channel (1) is the only primary process. In view of these inconsistencies we are unable to recommend Br atom quantum yields for λ <300 nm. Note that regardless of whether Br or Br are formed, any Br will be rapidly photodissociated to 2Br in the sunlit atmosphere. 2 2 References Bayes, K. D., Toohey, D. W., Friedl, R. R. and Sander, S. P.: J. Geophys. Res., 108, No D3, 4095, doi:10.29/2002 JD002877, Gillotay, D., Jenouvrier, A., Coquart, B., Merrienne, M. F. and Simon, P. C.: Planet. Space Sci. 37, 1127, 1989. Huang, H-Y., Chuang, W-T., Shama, R. C., Hsu, C-Y., Lin, K-C. and Hu, C-H.: J. Chem. Phys., 121, 5253, 2004. McGivern, W. S., Sorkhabi, O., Suits, A. G., Derecskei-Kovacs, A. and North, S.W.: J. Phys. Chem., A 104, 10085, 2000. Moortgat, G. K., Meller, R. and Schneider, W.: pp. 359–369, in ”The Tropospheric Chemistry of Ozone in the Polar Regions,” Niki, H. and Becker, K. H. editors, NATO ASI Series, Volume 17, Springer-Verlag, Berlin, 1993. Peterson, K. A. and Francisco, J. S.: J. Chem. Phys., 117, 6103, 2002. Xu, D., Francisco, J. S., Huang, J. and Jackson, W. M.: J. Chem. Phys., 117, 2578, 2002. Zou, P., Shu, J., Sears, T., Hall, G. E. and North, S. W.: J. Phys. Chem., A 108, 1482, 2004. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4473 IV.A4.264 CF BrCF Br + hν → products 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CF BrCF Br + hν → CF BrCF + Br 280 (est) 427 2 2 2 2 Absorption cross-section data Wavelength range/nm Reference Comments 170–302 Gillotay et al., 1988 (a) 190–320 Burkholder et al., 1991 (b) 190-304 Orkin and Kasimovskaya, 1995 (c) Quantum yield data Measurement Wavelength range/nm Reference Comments 8(Br) = 1.9± 0.1 193 Zou et al., 2000 (d) 8(Br) = 1.9± 0.1 233 8(Br) = 1.4± 0.1 266 Comments (a) Spectra were obtained using a thermostatted absorption cell with a single pass optical path of 2 m coupled to a monochro- mator capable of a maximum resolution of 0.015 nm. Spectra were recorded at 295 K, 270 K, 250 K, 230 K and 210 K. The data were ﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. (b) Spectra were obtained using a thermostatted absorption cells with single pass optical paths of 98.1 cm and 150 cm, coupled to spectrographs having resolutions in the range 0.4–0.5 nm. Spectra were recorded at 296 K, 270 K, 250 K, 230 K and 210 K. The data were ﬁtted to a polynomial expression giving the cross sections as a function of temperature and pressure. (c) Spectra were obtained using a cell thermostatted at 295 K with a single path optical length of 14.0 cm and coupled to a double beam spectrophotometric system. Sample pressures in the range 0.65–160 mbar were used. (d) Product branching ratios, angular and translational distributions measured using photofragment translational spectroscopy, following laser photodissociation of CF BrCF Br. Detection by VUV ionisation or REMPI. 2 2 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4474 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values Absorption cross-sections of CF BrCF Br at 296 K and 210 K. 2 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 295 K 210 K 295 K 210 K 190 108 119 240 13.4 11.5 192 114 124 242 10.7 8.95 194 119 128 244 8.47 6.89 196 123 131 246 6.69 5.25 198 125 133 248 5.23 2.95 200 125 133 250 4.05 2.93 202 125 132 252 3.09 2.15 204 121 129 254 2.36 1.56 206 117 125 256 1.77 1.13 208 112 119 258 1.32 0.807 210 105 112 260 0.978 0.576 212 98.6 104 262 0.724 0.391 214 94.5 96.1 264 0.535 0.275 216 83.4 85.0 266 0.394 0.191 218 75.6 79.0 268 0.290 0.134 220 67.8 70.3 270 0.212 0.093 222 60.2 62.0 272 0.155 224 53.0 54.3 274 0.112 226 46.2 46.8 276 0.082 228 40.0 40.1 278 0.060 230 34.2 33.9 280 0.044 232 29.0 27.9 234 24.3 22.6 236 20.1 18.2 238 16.5 14.5 Quantum Yields 8 (Br) = 2 (in stratosphere). 8 (Br) = 1 (in troposphere). Comments on Preferred Values The preferred values for the absorption cross-sections at 295 K are the means of the values reported by Gillotay et al. (1988), Burkholder et al. (1991) and Orkin and Kasimovskaya (1995). Values at 5 nm intervals have also been reported by Molina et al. (1982). The agreement among the four studies (Gillotay et al., 1988; Burkholder et al., 1991; Orkin and Kasimovskaya, 1995; Molina et al., 1982) over the wavelength range of the preferred values is very good. The temperature dependence down to 210 K has been studied by Gillotay et al. (1988) and Burkholder et al. (1991). There are signiﬁcant differences between the two studies (Gillotay et al.,1988; Burkholder et al., 1991). Close to the absorption peak (∼200 nm) Burkholder et al. (1991) report a 20% increase in the absorption cross-section in going from 295 K to 210 K, whereas Gillotay et al. (1988) report a small decrease. Furthermore, at 210 K the values of the cross-section obtained by Gillotay et al. (1988) are only ∼4% lower than those of Burkholder et al. (1991) at short wavelengths but this difference increases in going to longer wavelengths, reaching ∼40% at 270 nm. Provisionally, the preferred values at 210 K are taken as the mean of the values of Gillotay et al. (1988) and Burkholder et al. (1991). Photolysis is expected to occur with unit quantum efﬁciency by rupture of the C-Br bond to give CF BrCF + Br and prompt 2 2 dissociation of nascent CF BrCF to give a second Br atom is likely to predominate in stratospheric photolysis, which is the 2 2 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4475 main atmospheric sink. CF BrCF Br has been estimated to have a tropospheric lifetime against direct solar photolysis of 34 2 2 years (Burkholder et al., 1991). References Burkholder, J. B., Wilson, R. R., Gierczak, T., Talukdar, R., McKeen, S. A., Orlando, J. J., Vaghjiani, G. L. and Ravishankara, A. R.: J. Geophys. Res. 96, 5025, 1991. Gillotay, D., Simon, P. C. and Dierickx, L.: Aeronomica Acta 335, 1, 1988. Molina, L. T., Molina, M. J. and Rowland, F. S.: J. Phys. Chem. 86, 2672, 1982. Orkin, V. L. and Kasimovskaya, E. E.: J. Atmos. Res. 21, 1, 1995. Zou, P., McGivern, W. S., Sorkhabi, O., Suits, A. G. and North, S. W.: J. Chem. Phys., 113, 7149, 2000. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4476 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A4.265 CH Br + hν → products 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CH Br + hν → CH Br + Br 292 410 2 2 2 Absorption cross-section data Wavelength range/nm Reference Comments 200–300 Molina et al., 1982 (a) 174–290 Gillotay et al., 1988 (b) 215-300 Mossinger ¨ et al., 1998 (c) Quantum yield data No experimental data are available. Comments (a) The cross-sections were measured using a double beam spectrophotometer equipped with 10 cm and 180 cm cells. Pres- sures in the range 8–52 mbar were used. (b) Spectra were obtained using a thermostatted absorption cell with a single pass optical path of 2 m coupled to a monochro- −2 mator capable of a maximum resolution of 0.015 nm. Pressures of CH Br used covered the range 0.05–47× 10 mbar. 2 2 Spectra were recorded at 295 K, 270 K, 250 K, 230 K and 210 K. (c) Spectra were obtained using a thermostatted absorption cell of optical path length 100 cm coupled to a double beam optical system giving a resolution of∼ 0.6 nm. Pressures used were in the range 0.13–53 mbar. Absorption measurements were made at 348 K, 328 K, 298 K, 273 K and 250 K. At each wavelength the temperature dependence of the cross-sections was expressed as ln σ = ln σ + B (T - 298) and values of B were derived. T 298 K Preferred Values Absorption cross-sections of CH Br at 298 K and 210 K. 2 2 20 2 20 2 20 2 20 2 λ/nm 10 σ /cm 10 σ /cm λ/nm 10 σ /cm 10 σ /cm 298 K 210 K 298 K 210 K 200 226 223 255 14.1 8.51 205 215 206 260 6.61 3.38 210 235 240 265 3.03 1.34 215 263 325 270 1.34 0.506 220 272 356 275 0.514 0.199 225 247 318 280 0.255 0.0773 230 196 239 285 0.114 0.0324 235 139 154 290 0.0499 0.0140 240 88.6 86.1 295 0.0165 0.0049 245 51.9 43.6 300 0.006 0.0013 250 28.0 19.7 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4477 Quantum Yields 8 (Br) = 1 for λ > 240 nm. Comments on Preferred Values The preferred values for the absorption cross-sections at 298 K are the means of the values reported by Molina et al. (1982), Gillotay et al. (1988) and Mossinger ¨ et al. (1998). The agreement among the three studies (Molina et al., 1982; Gillotay et al., 1988; Mossinger ¨ et al., 1998) over the wavelength range of the preferred values is excellent. The temperature dependence of σ over the range 210–295 K has been studied by Gillotay et al. (1988) and over the range 250–348 K by Mossinger ¨ et al. (1998). The results agree well in the region where they overlap and both ﬁnd that σ increases with decreasing temperature at the absorption band maximum (219 nm) but shows a decrease with temperature decrease in the long wavelength tail of the spectrum. The preferred values at 210 K are those of Gillotay et al. (1988) which are in very good agreement with the values calculated from the expression and temperature coefﬁcients of Mossinger ¨ et al. (1998), based on their measurements in the range 250–348 K. There are no quantum yield measurements but an investigation of the photodissociation at 248 nm using product translational spectroscopy shows that CH Br undergoes a simple C-Br ﬁssion (Lee et al., 2003). 2 2 References Gillotay, D., Simon, P.C. and Dierickx, L.: Aeron. Acta 35, 1, 1988. Lee, Y-R., Chen, C-C. and Lin, S-W.: J. Chem. Phys., 118, 10494, 2003. Molina, L. T., Molina, M. J. and Rowland, F. S.: J. Phys. Chem. 86, 2672, 1982. Mossinger ¨ , J. C., Shallcross, D. E. and Cox, R. A.: J. Chem. Soc. Faraday Trans. 94, 1391, 1998. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4478 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Appendix 4: IO Reactions IV.A4.266 HO + CH I→ H O + CH I 3 2 2 ◦ −1 1H = -63.1 kJ·mol Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −12 3.1× 10 exp[-(1119± 205)/T ] 271-423 Brown et al., 1990 DF-RF −14 (7.2± 0.7)× 10 298 −13 (1.2± 0.4)× 10 299 Gilles et al., 1996 PLP-LIF (a) −14 (9.9± 2.0)× 10 298± 2 Cotter et al., 2003 DF-RF Comments (a) Derived from the time-concentration proﬁles of HO radicals monitored by LIF after generation of O( P) atoms (from 193 nm pulsed laser photolysis of N O in N ) in the presence of varying amounts of CH I. 2 2 3 Preferred Values −13 3 −1 −1 k = 1.0× 10 cm molecule s at 298 K. −12 3 −1 −1 k = 4.3× 10 exp(-1120/T ) cm molecule s over the temperature range 270-430 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values The room temperature rate coefﬁcients of Brown et al. (1990), Gilles et al. (1996) and Cotter et al. (2003) are in reasonable agreement, and the preferred 298 K rate coefﬁcient is an average of the room temperature rate coefﬁcients from these three studies. The temperature dependence obtained by Brown et al. (1990), the only temperature-dependent study to date, is accepted and the pre-exponential factor is adjusted to ﬁt the 298 K preferred value. References Brown, A. C., Canosa-Mas, C. E. and Wayne, R. P.: Atmos. Environ., 24A, 361, 1990. Cotter, E. S. N., Canosa-Mas, C. E., Manners, C. R., Wayne, R. P. and Shallcross, D. E.: Atmos. Environ., 37, 1125, 2003. Gilles, M. K., Turnipseed, A. A., Talukdar, R. K., Rudich, Y., Villalta, P. W., Huey, L. G., Burkholder, J. B. and Ravishankara, A. R.: J. Phys. Chem., 100, 14005, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4479 IV.A4.267 HO + CF I→ products Rate coefﬁcient data 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −13 (1.2± 0.2)× 10 295 Garraway and Donovan, 1979 FP-RA −14 (3.1± 0.5)× 10 300 Brown et al., 1990 DF-RF −12 5.8× 10 exp[-(1359± 133)/T ] 281-443 Berry et al., 1998 FP-RF (a) −14 (5.9± 1.4)× 10 292 −11 2.1× 10 exp[-(2000± 140)/T ] 271-370 Gilles et al., 2000 PLP-LIF (b) −14 (2.35± 0.54)× 10 296 Comments (a) The measured rate coefﬁcients were observed to increase with ﬂash energy (which affects both the initial concentration of HO radicals and the amount of CF I photolysis products). The cited rate coefﬁcients at each temperature were obtained from extrapolation to zero ﬂash energy. Theoretical calculations indicated that the dominant channel is that to form CF + HOI. (b) No effect on the rate coefﬁcient of varying the laser ﬂuence by a factor of ∼5 was observed when 351 nm pulsed laser photolysis of HONO was used as the HO radical source. However, a signiﬁcant effect of laser ﬂuence was observed when using 248 nm pulsed laser photolysis of O in the presence of H O to generate HO radicals. The cited rate coefﬁcients 3 2 and Arrhenius expression were obtained from experiments using 351 nm photolysis of HONO as the HO radical source. The CF I concentrations were monitored by UV/visible absorption spectroscopy. Preferred Values −14 3 −1 −1 k = 2.6× 10 cm molecule s at 298 K. −11 3 −1 −1 k = 2.1× 10 exp(-2000/T ) cm molecule s over the temperature range 270-370 K. Reliability 1 log k =± 0.2 at 298 K. 1 (E/R) =± 500 K. Comments on Preferred Values Studies of this reaction have the potential for secondary reactions (including, in the pulsed photolysis systems, with CF I photolysis products), reactions with impurities, and/or heterogeneous wall reactions (Brown et al., 1990; Wayne et al., 1992; Berry et al., 1998; Gilles et al., 2000). The preferred values are based on the more extensive study of Gilles et al. (2000) in which HONO photolysis at 351 nm was used to generate HO radicals with no apparent problems due to secondary reactions and with the CF I concentrations being monitored by UV/visible absorption spectroscopy. References Berry, R. J., Yuan, J., Misra, A. and Marshall, P.: J. Phys. Chem. A, 102, 5182, 1998. Brown, A. C., Canosa-Mas, C. E. and Wayne, R. P.: Atmos. Environ., 24A, 361, 1990. Garraway, J. and Donovan, R. J.: J. Chem. Soc., Chem. Comm. 1108, 1979. Gilles, M. K., Talukdar, R. K. and Ravishankara, A. R.: J. Phys. Chem. A, 104, 8945, 2000. Wayne, R. P., Canosa-Mas, C. E., Heard, A. C. and Parr, A. D.: Atmos. Environ., 26A, 2371, 1992. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4480 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A4.268 CH IO + CH IO → CH IOH + HC(O)I + O (1) 2 2 2 2 2 2 → 2CH IO + O (2) 2 2 Rate coefﬁcient data (k = k + k ) 1 2 3 −1 −1 k/cm molecule s Temp./K Reference Technique/Comments Absolute Rate Coefﬁcients −11 ∼9× 10 295± 2 Sehested et al., 1994 (a) Comments (a) Pulse radiolysis UV absorption spectrometric study of CH I-O -SF mixtures at a total pressure of 1000 mbar. CH IO 3 2 6 2 2 −18 2 −1 radicals were monitored by UV absorption with σ = (2.1 ± 0.5) × 10 cm molecule . The interpretation of the kinetic data is complicated by the presence of CH O radicals, which leads to mixed-order kinetics. The above 3 2 approximate value of k was derived on the basis of several assumptions. Preferred Values No recommendation Comments on Preferred Values The approximate and exceptionally large rate coefﬁcient obtained by Sehested et al. (1994) should be regarded with caution owing to the inherent complications in their experimental system. Until more work is carried out in this reaction, we make no recommendation. References Sehested, J., Ellermann, T. and Nielsen, O. J.: Int. J. Chem. Kinet. 26, 259, 1994. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4481 IV.A4.269 CH I + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CH I + hν → CH + I( P ) (1) 239 541 3 3 3/2 → CH + I( P ) (2) 330 362 3 1/2 → CH + HI (3) 403 297 Absorption cross-section data Wavelength range/nm References Comments 210–360 Jenkin et al., 1993 (a) 160–400 Fahr et al., 1995 (b) 200-380 Roehl et al., 1997 (c) 235-350 Rattigan et al., 1997 (d) Quantum yield data Measurement Wavelength range/nm References Comments 8(I ) 254 Christie, 1958 (e) 2 2 8{I( P ); I( P )} 266 Riley and Wilson, 1972 (f) 1/2 3/2 8{I( P )} 248-308 Baughcum and Leone, 1980 (g) 1/2 2 2 8{I( P ); I( P )} 247.5-312.5 Hunter et al., 1983 (h) 1/2 3/2 8I( P )=0.07± 0.02 304 Li et al., 2005 (i) 1/2 8I( P )=0.93± 0.02 304 3/2 Comments (a) The absorption spectrum of CH I was recorded by diode array spectroscopy with a resolution of approx. 1 nm using a puriﬁed sample. Tabulated cross section values for the indicated range were given, showing a single absorption band extending from 210 to 365 nm. The absolute cross-section at the maximum of absorption at 257.9 nm was σ = 1.22 × −18 2 −1 10 cm molecule , which was in good agreement with the earlier published spectrum of Porret and Goodeve (1937). (b) Absorption spectrum measured over temperature range 223–333 K at a resolution of 0.1 nm; cross sections at 0.5 nm intervals given. In addition to the gas phase measurements over the wavelength range 160–335 nm, liquid phase measure- ments over the range 330–400 nm were also reported. A wavelength shift was applied to convert the liquid phase data to accurate gas phase cross sections at the long wavelengths. (c) Absorption coefﬁcients for CH I were determined by diode array spectrometry with a spectral resolution of 0.6 nm. Tabulated cross section values for the indicated range were given. A single absorption band was observed to extend from −18 2 < 230 nm to 365 nm with a maximum at 260 nm where the absorption cross section was σ = (1.09±0.08)× 10 cm −1 molecule at 298 K. The temperature dependence of the absorption cross section was determined over the range 243–333 K; broadening of the band was observed giving a signiﬁcant decline in σ with decreasing temperature in the tropospheric photolysis region (λ > 290 nm). (d) The absorption spectrum of CH I (purity > 98%) was recorded by diode array spectrometry with a resolution of 0.3 nm. Tabulated cross section values for the indicated range were given. The absolute cross-section at the maximum of −18 2 −1 absorption at 260 nm was σ = 1.13 × 10 cm molecule with a stated overall uncertainty of ±5%. Signiﬁcant www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4482 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry temperature dependence of the absorption cross section was observed over the range 228–298 K, with a decrease in σ with decreasing temperature in the long wavelength tail. A second absorption band is indicated by an increase in σ below 210 nm. (e) Photo-oxidation of CH I; measurement of loss of CH I and yield of I product. 3 3 2 8(-CH I) = 1.0; 8(I ) = 0.5. 3 2 (f) Translational energy of the I atoms produced in 266 nm photolysis of CH I in a molecular beam. Suggested the following primary processes: CH I + hν → CH + I( P ) 3 3 3/2 CH I + hν → CH + I( P ) 3 3 1/2 with I( P ) production at 78% of the primary process. 3/2 2 2 (g) Pulsed tunable laser photolysis of CH I, with I( P ) detection by infra-red ﬂuorescence at 1.315 μm. 8{I( P )} 3 1/2 1/2 increased from 0.05 to 0.81 over the wavelength range 308–248 nm. 2 2 (h) Branching ratio for I( P )/I( P ) as a function of wavelength determined by an optical acoustic method. 1/2 3/2 2 2 (i) Crossed beam Laser photolysis - core sampling photofragment translational spectroscopy study. I( P ) and I( P ) 1/2 3/2 detected by REMPI + pulsed acceleration TOF MS, giving high kinetic resolution. The 8I( P ) 2 + 1 is determined 1/2 relative to the total I atom yield, using a calibration method reported by Kang et al. (1996). Preferred Values Absorption cross-sections of CH I at 298 K 20 2 3 −1 Wavelength/nm 10 σ /cm 10 B /K 205 7.0 210 3.8 215 5.2 220 6.9 225 9.1 230 12.6 235 20.2 0.67 240 37.4 0.61 245 63.6 0.34 250 92.1 0.08 255 111.1 -0.1 260 112.3 -0.12 265 96.6 0.1 270 71.7 0.54 275 47.1 1.33 280 28.0 2.43 285 15.2 3.74 290 7.79 4.98 295 3.92 6.38 300 2.03 6.97 305 1.09 6.82 310 0.619 6.78 315 0.356 6.95 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4483 20 2 3 −1 Wavelength/nm 10 σ /cm 10 B /K 320 0.215 6.94 325 0.124 6.79 330 0.070 7.82 335 0.033 9.34 340 0.023 10.95 345 0.0127 13.58 350 0.0067 16.83 355 0.0026 18.91 360 0.0013 17.28 365 0.0004 23.63 Temperature dependence given by: ln σ = ln σ (298) + B(T -298/K) Quantum Yield 8 + 8 = 1.0 over the wavelength range 210–360 nm. 1 2 Comments on Preferred Values Porret and Goodeve (1937) measured the absolute absorption cross-sections of methyl iodide in the range 200–360 nm in their pioneering work on the quantitative investigation of electronic spectra of simple molecules. The ﬁrst absorption band extends from 360 nm to∼ 210 nm and is attributed to a σ → n transition. The reported cross sections of Jenkin et al. (1993), Rattigan et al. (1997) and Roehl et al. (1997) are in good agreement with each other and with those in the earlier published study (Porret and Goodeve, 1937). The results of Fahr et al. (1995) agree well with the other measurements at λ > 300 nm, but are signiﬁcantly higher by ∼20% at the maximum of absorption. The preferred values for the cross-sections at 298 K are based on the data for the absolute absorption cross-sections reported by Jenkin et al. (1993), Rattigan et al. (1997) and Roehl et al. (1997). The listed values are actual values at 1 nm intervals. The effect of temperature on the absorption cross-section has been studied by Fahr et al. (1995), Rattigan et al. (1997) and Roehl et al. (1997). All studies show excellent agreement for the temperature dependence and reveal an apparent narrowing of the band as temperature decreases, leading to an increase in σ at the band head and a decrease in σ in the long wavelength tail of absorption. The temperature dependence of CH I absorption has also been investigated by Waschewsky et al. (1996) who argue that the temperature-dependent cross section measurements are complicated by the presence of dimers and therefore do not apply to atmospheric spectra. Analysis by Rattigan et al. (1997) and Roehl et al. (1997) of their measurements taken over an extensive range of pressures and temperatures shows that the effect of dimers must be completely negligible for their experimental conditions. The recommended temperature dependence, expressed in terms of a single parameter B in the equation: ln σ = ln σ (298) + B (T -298/K) from the work of Rattigan et al. (1997) is adopted. The photochemistry of alkyl iodides has been extensively studied since the early investigations of photolytic reactions and has been reviewed by Majer and Simons (1964), Calvert and Pitts (1966) and Okabe (1978). For methyl iodide the primary process is dissociation into a methyl radical and an iodine atom, processes (1) and (2), occurring with a quantum yield of unity. Reaction (3) may be important following absorption in the vacuum uv (Riley and Wilson, 1972). The primary photodissociation processes have been studied extensively in conjunction with the laser emission: I( P )→ 1/2 I( P ) + hν observed at 1.315 μm in the near-UV ﬂash photolysis of CH I (Kasper and Pimentel, 1964). State-selected 3/2 3 photofragment spectroscopy has shown that I atoms are produced in both the ground I( P ) and the electronically excited 3/2 2 2 I( P ) state. The relative yields of I( P ) increases with decreasing wavelength below 304 nm to a maximum near the 1/2 1/2 maximum in the A-band absorption of CH I near 260 nm. This can be rationalised in terms of the correlations of I( P ) and 3 1/2 2 3 1 3 I( P ) states with the Q , Q and Q electronic states, which have λ at 261 nm, 240 nm and 300 nm respectively 3/2 o+ 1 1 max (Gedanken et al., 1975). www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4484 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry References Baughcum, S. L. and Leone, J.: Chem. Phys. 72, 6531, 1980. Calvert, J. G. and Pitts, J. N. Jr.: ’Photochemistry’ J. Wiley New York 1966. Christie, M. I. : Proc. Roy. Soc. (London) A 244, 411, 1958. Fahr, A., Nayak, K. A. and Kurylo, M. J.: Chem. Phys. 197, 195, 1995. Gedanken, A. and Rowe, H. D.: Chem. Phys. Lett., 34, 39, 1975. Hunter, T. F., Lunt, S. and Kristjansson, K. S.: J. Chem. Soc. Faraday Soc. 79, 303, 1983. Jenkin, M. E., Murrells, T. P., Shalliker, S. J. and Hayman, G. D. : J. Chem. Soc. Faraday Soc. 89, 433, 1993. Kang, W. K., Jung, K. W., Kim, D.-C. and Jung, K. H.: J. Chem. Phys., 104, 5815, 1996. Kasper, J. V. V. and Pimentel, G. C.: Appl. Physics Lett. 5, 231 1964. Li, G., Shin, Y. K. and Hwang, H. J.: J. Phys. Chem. A 109, 9226, 2005. Majer, J. R. and Simons, J. P.: Adv. Photochem. 2, 137, 1964. Okabe, H.: ”Photochemistry of Small Molecules”, Wiley Interscience, 1978. Porret, D. and Goodeve, C. F.: Trans. Faraday Soc. 33, 690, 1937. Rattigan, O. V., Shallcross, D. E. and Cox, R. A.: J. Chem. Soc. Faraday Trans. 93, 690, 1997. Riley, S. J. and Wilson, K. R.: Disc. Faraday Soc. 53, 132, 1972. Roehl, C. M., Burkholder, J. B., Moortgat, G. K., Ravishankara, A. R. and Crutzen, P. J.: J. Geophys. Res. 102, 12819, 1997. Waschewsky, G. C., Horansky, R. and Vaida, V.: J. Phys. Chem. 100, 11559, 1996. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4485 IV.A4.270 CF I + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CF I + hν → CF + I( P ) (1) 230 521 3 3 3/2 → CF + I( P ) (2) 320 374 3 1/2 Absorption cross-section data Wavelength range/nm References Comments 216–370 Solomon et al., 1994 (a) 160–340 Fahr et al., 1995 (b) 235–400 Rattigan et al., 1997 (c) Quantum yield data Measurement Wavelength range/nm References Comments 2 2 8{I( P ); I( P )} 266 Riley and Wilson, 1972 (d) 1/2 3/2 2 2 8{I( P ); I( P )} 304 Kang et al., 1996 (e) 1/2 3/2 2 2 8{I( P ); I( P )} 275-303 Furlan et al., 1996 (f) 1/2 3/2 Comments (a) Absorption coefﬁcients for puriﬁed CF I determined by diode array spectrometry, over temperature range 200–298 K. A single absorption band was observed to extend from 370–210 nm with a maximum at 267 nm where the absorption −18 2 −1 coefﬁcient was σ = 6.0× 10 cm molecule . (b) The absorption spectrum of CF I was recorded by diode array spectrometry with a resolution of approx. 1 nm using −18 2 a puriﬁed sample. The absolute cross-section at the maximum of absorption at 267 nm was σ = 6.8 × 10 cm −1 molecule . A second band extends into the vacuum UV. The temperature dependence over the wavelength range 160– 240 nm was determined at 240, 295 and 355 K; and over the range 240–350 nm for 218–333 K. (c) The absorption spectrum of CF I was recorded by diode array spectrometry with a resolution of approx. 0.6 nm using a −18 2 puriﬁed sample. The absolute cross-section at the maximum of absorption at 267 nm was σ = (6.0±0.1) × 10 cm −1 molecule . A second band extends into the vacuum UV. The temperature dependence was determined for 243–333K. (d) Translational energy of the I atoms produced in 266 nm photolysis of CF I in a molecular beam. Suggested the following primary processes: CF I + hν → CF + I( P ) 3 3 3/2 CF I + hν → CF + I( P ) 3 3 1/2 with I( P ) production at 78% of the primary process. 3/2 2 2 (e) Relative yield of I( P )/I( P ) determined by (2+1) REMPI and pulsed ﬁeld TOF-MS following laser photodissocia- 1/2 3/2 tion of CF I. 8{I( P )} = 0.69. 3 1/2 2 2 (f) Relative yield of I( P )/I( P ) obtained by high resolution photofragment translational spectrometry using pulsed laser 1/2 3/2 photolysis and TOF-MS. 8{I( P )} increased from 0.38 at 303 nm to 0.92 at 275 nm. 1/2 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4486 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values Absorption cross-sections of CF I at 298 K 20 2 3 −1 Wavelength/nm 10 σ /cm 10 B /K 235 7.5 0.155 240 13.4 0.21 245 21.4 -0.121 250 32.5 -0.45 255 45.5 -0.766 260 57.3 -0.992 265 64.2 -1.07 270 63.9 -0.936 275 56.9 -0.554 280 45.6 -0.0505 285 33.8 1.02 290 23.0 2.18 295 14.6 3.34 300 8.81 4.56 305 5.13 5.81 310 2.88 6.82 315 0.907 7.89 325 0.49 8.22 330 0.263 8.57 335 0.144 9.06 340 0.0771 9.98 345 0.0393 10.9 350 0.0208 12.5 355 0.0115 13.3 360 0.0064 14.6 365 0.0036 14.6 370 0.002 15.5 375 0.0011 17.1 380 0.0007 17.7 385 0.0004 19.7 390 0.0001 22.6 Temperature dependence given by: ln σ = ln σ (298) + B (T -298/K) Quantum Yield 8 + 8 = 1.0 over the wavelength range 210–360 nm. 1 2 Comments on Preferred Values There is excellent agreement between all three reported data sets for the cross section and its temperature dependence. The maximum of the ﬁrst absorption band is lower and red-shifted compared with methyl iodide. The band narrowed with decreas- ing temperature leading to a signiﬁcant decrease in the cross section in the long wavelength tail; at 320 nm the value decreases by nearly 50% at 200 K. The recommended values for σ and its temperature dependence are the mean of all three studies (Solomon et al., 1994; Fahr et al., 1995; Rattigan et al. 1997). Photolysis is expected to occur with quantum efﬁciency by breaking of the C-I bond to yield CF + I. State-selected photofragment spectroscopy has shown that I atoms are produced predominantly in the excited state I( P ), following pho- 1/2 2 2 todissociation of CF I near the band maximum. The branching ratio for: I( P )/I( P ) production decreases at longer 3 1/2 3/2 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4487 wavelengths but there is some disagreement in the actual values (Riley and Wilson, 1972; Kang et al., 1996; Furlan et al., 1996). References Fahr, A,. Nayak, A. K. and Huie, R. E.: Chem. Phys. 199, 275, 1995. Furlan, A., Gejo, T. and Huber, J. R.: J. Phys. Chem. 100, 7956, 1996. Kang, W. K., Jung, K. W., Kim, D. C. and Jung, H. H.: J. Chem. Phys. 104, 5815, 1996. Rattigan, O. V., Shallcross, D. E. and Cox, R. A.: J. Chem. Soc. Faraday Trans. 93, 2839, 1997. Riley, S. J. and Wilson, K. R.: Disc. Faraday Soc. 53, 132, 1972. Solomon, S., Burkholder, J. B., Ravishankara, A. R. and Garcia, R. R.: J. Geophys. Res. 99, 20929, 1994. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4488 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A4.271 CH ClI + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CH ClI + hν → CH Cl + I (1) 217 551 2 2 → CH I + Cl (2) 344 347 Absorption cross-section data Wavelength range/nm Reference Comments 235–390 Rattigan et al., 1997 (a) 200–380 Roehl et al., 1997 (b) Quantum yield data Measurement Wavelength range/nm Reference Comments 8(I ) 266 Schmitt and Comes, 1987 (c) 8{I( P )} = 0.44 222 Senapati et al., 2002 (d) 1/2 8{I( P )} = 0.50 236 1/2 8{I( P )} = 0.50 266 1/2 8{I( P )} = 0.55 280 1/2 8{Cl( P )} = 0.34 304 Senapati and Das, 2004 (e) 1/2 8{Cl( P )} = 0.44 222 1/2 8{Cl( P )} = 0.44 266 1/2 8{Cl( P )} = 0.30 280 1/2 8{Cl( P )} = 0.22 304 1/2 Comments (a) Absorption coefﬁcients for CH CII (purity 98%) were determined by diode array spectrometry with a spectral resolution of 0.6 nm. A single absorption band was observed to extend from 230–400 nm with a maximum at 270 nm where −18 2 −1 the absorption coefﬁcient was σ = (1.21 ± 0.07) × 10 cm molecule at 298 K. The temperature dependence of the absorption cross section was determined over the range 243-333 K; broadening of the band was observed giving a signiﬁcant decline in σ with decreasing temperature in the tropospheric photolysis region (λ > 290 nm). (b) The absorption spectrum of CH ClI (purity 97%) was recorded by by diode array spectrometry with a resolution of 0.3 −18 2 −1 nm. The absolute cross section at the maximum of absorption at 270 nm was σ = 1.35 × 10 cm molecule with a stated overall uncertainty of± 5%. Signiﬁcance temperature dependence of the absorption cross section was observed over the range 228-298 K, with a decrease in σ with a decrease in temperature in the long wavelength tail. A second absorption band is indicated by an increase in σ below 220 nm. (c) Laser photolysis of CH ClI; measurement of yield of I by time resolved laser absorption spectroscopy at 514.5 nm. 2 2 2 2 (d) Laser Photolysis-REMPI detection of I( P ) and I( P ). 1/2 3/2 2 2 2 (e) Laser Photolysis-REMPI detection of Cl( P ) and Cl( P ). 8 determined relative to 8{I( P )} production at the 1/2 3/2 1/2 same wavelength. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4489 Preferred Values Absorption cross-sections of CH ClI at 298 K 20 2 3 −1 Wavelength/nm 10 σ /cm 10 B /K 205 122 210 39.1 215 10.3 220 7.0 225 9.06 230 13.8 235 21.2 0.24 240 31.8 0.122 245 45.6 -0.018 250 62.9 -0.114 255 84 -0.283 260 105 -0.444 265 121 -0.547 270 127 -0.587 275 120 -0.47 280 103 -0.18 285 80.7 0.317 290 58.1 0.985 295 39.8 1.73 300 25.9 2.56 305 16.7 3.08 310 10.9 3.5 315 7.16 3.56 320 4.79 3.46 325 3.23 3.44 330 2.14 3.72 335 1.4 4.09 340 0.905 4.87 345 0.569 5.69 350 0.35 6.88 355 0.225 8.16 360 0.138 9.01 365 0.081 11.1 370 0.048 11.5 375 0.027 12.8 380 0.017 15.1 385 0.008 19.1 390 0.006 20.5 Temperature dependence given by: ln σ = ln σ (298) + B (T -298/K) Quantum Yield 8 + 8 = 1.0 over the wavelength range 230–390 nm; no recommendation for 8 /8 1 2 2 1 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4490 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values The data of Rattigan et al. (1997) and Roehl et al. (1997) are in excellent agreement both in terms of the absolute absorption cross sections, and their temperature dependence as a function of wavelength. The earlier data of Schmitt and Comes (1987) −18 2 −1 also showed a maximum at 270 nm but the absolute cross section was higher (1.5 × 10 cm molecule ). The preferred values for the cross-sections are a simple mean of data of Rattigan et al. (1997) and Roehl et al. (1997), and the temperature dependence, expressed in terms of a single parameter B in the equation: ln σ = ln σ (298) + B(T - 298/K) from the work of Rattigan et al. (1997) is adopted. The photodecomposition of CH ClI studied by Schmitt and Comes (1987) indicated dissociation via reaction (1), in line with other alkyl iodides, occurring with a quantum yield of unity. The quantum yield of I( P ) are reported by Senapati 1/2 et al., (2002), who observed a similar trend with wavelength as that observed for photolysis of CH I. This suggests that the photodissociation occurs from 3 upper states similar to methyl iodide. However, Senapati and Das 2004 observed Cl( P ) 1/2 production and measured yields (relative to I( P )), which decrease with increasing wavelength in the range 222≤ λ≤ 304 1/2 nm. An inter-chromophore energy transfer mechanism between C-I and C-Cl chromophore is proposed to rationalise Cl( P ) 1/2 production. On the basis of available data it is not possible to recommend a branching ratio for Cl atom formation, but I atom production will predominate in tropospheric photolysis. References Rattigan, O. V., Shallcross, D. E. and Cox, R. A.: J. Chem. Soc. Farad. Trans. 93, 2839, 1997. Roehl, C. M., Burkholder, J. B., Moortgat, G. K., Ravishankara, A. R. and Crutzen, P. J.: J. Geophys. Res. 102, 12819, 1997. Schmitt, G. and Comes, F. J.: J. Photochem. Photobiol. A, 41, 13, 1987. Senapati, D., Kavita, K. and Das, P. K.: J. Phys. Chem. A, 106, 8479, 2002. Senapati, D. and Das, P. K.: Chem. Phys. Lett., 393, 535, 2004. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4491 IV.A4.272 CH BrI + hν → products Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CH BrI + hν → CH Br + I (1) 214 559 2 2 → CH I + Br (2) 280 427 → CH + IBr (3) 369 324 Absorption cross-section data Wavelength range/nm Reference Comments 215–390 Mossinger et al., 1998 (a) Quantum yield data Measurement Wavelength range/nm Reference Comments 8 /8 = 6 240-340 Lee and Bersohn, 1982 (b) 1 2 8 /8 = 6 248 Butler et al., 1987 (c) 1 2 Comments (a) Absorption coefﬁcients for CH BrI (purity 98%) were determined by diode array spectrometry with a spectral resolution of 0.6 nm. The purity of the CH BrI sample was 92%, the main imputities being CH Br (6.5%) and CH I 1.5%). A 2 2 2 2 2 correction was applied for absorption by these impurities using spectra obtained in the same spectrometer. Tabulated cross section values for the indicated range were given. Two broad absorption bands attributed to CH BrI were observed with −18 2 −1 maxima at 215nm and 270 nm where the absorption cross sections were σ = (5.67±0.34)× 10 cm molecule and −18 2 −1 σ = (2.34±0.14) × 10 cm molecule respectively at 298 K. The temperature dependence of the absorption cross section was determined over the range 273-348 K; broadening of both bands was observed giving a signiﬁcant decline in σ with decreasing temperature in the tropospheric photolysis region (λ > 290 nm). (b) Photodissociation of CH BrI with broadband light source; dissociation fragments measured by mass spectrometry. Branching ratio for C-I and C-Br bond ﬁssion reported. These workers also reported a UV spectrum. (c) Product state distributions measured for laser photodissociation CH BrI at 193.3, 210, and 248.5 nm of in a molecular beam, using TOF-MS. At 248.5 nm both C-I and C-Br bond ﬁssion occurs, with I formation dominant, producing ground 2 2 state P and excited state P atoms in ratio of 1.0:0.75. At shorter wavelengths elimination of IBr was also observed. 3/2 1/2 www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4492 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Preferred Values Absorption cross-sections of CH BrI at 298 K 20 2 3 −1 Wavelength/nm 10 σ /cm 10 B /K 215 567 -2.16 220 423 -0.12 225 269 1.34 230 155 2.06 235 97.9 2.05 240 80.9 1.01 245 93.7 0.0 250 125 -0.58 255 170 -1.16 260 207 -1.29 265 228 -1.45 270 229 -1.73 275 214 -1.22 280 184 -0.94 285 150 -0.53 290 110 0.1 295 82.5 0.63 300 60.6 1.03 305 42.9 1.13 310 31.4 1.41 315 23.1 1.52 320 16.8 1.71 325 11.5 2.36 330 8.02 2.99 335 5.52 3.89 340 3.50 4.79 345 2.24 5.74 350 1.41 6.73 355 0.817 9.47 360 0.498 11.5 365 0.302 11.6 370 0.165 14.3 375 0.098 17.4 380 0.070 385 0.039 390 0.025 Temperature dependence given by: ln σ = ln σ (298) + B (T -298/K) Quantum Yield 8 = 1.0 over the wavelength range 290–380 nm. Comments on Preferred Values The preferred values for the cross sections and the temperature dependence are those of Mossinger ¨ et al. (1998), which appears to be the only reported study where absolute cross section were reported. Cross sections obtained for other halocarbons by this Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4493 group agree well with other literature data and the CH BrI data can be considered reliable. The absorption spectrum agrees with earlier reported spectra (Lee and R. Bersohn, 1982; Butler et al., 1987), which show two broad bands peaking at 270 nm and 215 nm which are assigned to promotion of electrons from non-bonding orbitals in the C-I and C-Br bonds respectively. The photodissociation of CH BrI via reaction (1) is expected to occur in the ﬁrst absorption band with a quantum yield of unity, in line with other alkyl iodides. Studies of the photodissociation fragments (Lee and Bersohn, 1982) show that reaction (2) is dominant following absorption in the second band at 210 nm and that both processes occur in the region where the bands overlap. In the region for tropospheric photolysis (λ > 290 nm) reaction (1) will dominate. References Butler, L. J., Hintsa, E. J,. Shane, S. F. and Lee, Y. T.: J. Phys. Chem. 86, 2051, 1987. Lee, S. J. and Bersohn, R.: J. Phys. Chem. 86, 728, 1982. Mossinger, J. C., Shallcross, D. E. and Cox, R. A.: J. Chem. Soc. Farad. Trans. 94, 1391, 1998. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4494 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry IV.A4.273 CH I + hν → products 2 2 Primary photochemical processes ◦ −1 Reaction 1H /kJ mol λ /nm threshold CH I + hν → CH I + I (1) 219 547 2 2 2 → CH + I (2) 335 357 2 2 Absorption cross-section data Wavelength range/nm Reference Comments 220–360 Schmitt and Comes, 1980 (a) 265–340 Koffend and Leone, 1981 (b) 200–380 Roehl et al., 1997 (c) 200–380 Mossinger ¨ et al., 1998 (d) Quantum yield data Measurement Wavelength range/nm Reference Comments 8(I ) 300 Schmitt and Comes, 1980 (e) 2 2 8{I( P ; I( P )} 254 Baughcum and Leone, 1980 (f) 1/2 3/2 8{I( P )} 248-340 Koffend and Leone, 1981 (g) 1/2 Comments (a) Conventional UV absorption spectrometry. The spectrum consisted of two asymmetrical peaks at 288 nm and 248 nm, suggesting several overlapping bands, and a third band below 220 nm. The absolute cross-section at the ﬁrst maximum of −18 2 −1 absorption at 290 nm was σ = 4.07× 10 cm molecule . (b) The absorption spectrum of CH I was recorded by conventional UV absorption spectrometry. The absolute cross-section 2 2 −18 2 −1 at the ﬁrst maximum of absorption at 286 nm was σ = 3.92× 10 cm molecule . (c) The absorption spectrum of CH I (purity 97%) was recorded by diode array spectrometry with a resolution of 0.3 nm. 2 2 The third absorption maximum occured at 210 nm. The absolute cross-section at the ﬁrst maximum of absorption at 290 −18 2 −1 nm was σ = 3.84 × 10 cm molecule with a stated overall uncertainty of ±5%. This was within 6% of the value of Schmitt and Comes (1980) and 2% of the Koffend and Leone data (1981). Signiﬁcant temperature dependence of the absorption cross section was observed over the range 273–298K, with a decrease in σ with decreasing temperature in the long wavelength tail. (d) Absorption coefﬁcients for CH I (purity 98%) were determined by diode array spectrometry with a spectral resolution 2 2 of 0.6 nm. Tabulated cross section values for the indicated range were given. The absolute cross-sections at absorption −18 2 −1 −18 2 maxima of 248 nm and 288 nm were σ = (1.62±0.10) × 10 cm molecule and σ = (3.78±0.23) × 10 cm −1 molecule , respectively, at 298 K. The temperature dependence of the absorption cross section was determined over the range 278-348 K; the temperature dependence was complex reﬂecting the presence of several overlapping bands but there was a signiﬁcant decline in σ with decreasing temperature in the tropospheric photolysis region (λ > 290 nm). (e) Pulsed laser photolysis of CH I ; measurement of yield of I by absorption spectrometry. Primary products deduced to 2 2 2 be I atoms, partially in the excited state. (f) Pulsed tunable laser photolysis of CH I , with I( P ) and excited CH I detection by infra red emission. 2 2 1/2 2 2 Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/ R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry 4495 2 2 (g) Pulsed tunable laser photolysis of CH I , with I( P ) detection by infra red ﬂuorescence at 1.315 μm. 8{I( P )} 2 2 1/2 1/2 increased from zero to 0.46 over the wavelength range 340 – 248 nm. Preferred Values Absorption cross-sections of CH I at 298 K 2 2 20 2 3 −1 Wavelength/nm 10 σ /cm 10 B /K 205 407 210 404 215 322 0.1515 220 260 0.14 225 198 0.19 230 132 0.51 235 109 0.56 240 123 0.15 245 150 0.18 250 157 0.67 255 140 1.58 260 120 2.04 265 130 1.30 270 179 0 275 255 -0.71 280 328 -1.24 285 373 -1.21 290 381 -0.94 295 372 -0.58 300 357 -0.37 305 338 0 310 314 0.07 315 280 0.15 320 244 0.27 325 203 0.27 330 161 0.51 335 120 0.55 340 83.3 1.36 345 53.7 1.99 350 32.6 3.19 355 19.2 4.09 360 10.9 5.39 365 6.05 6.77 370 3.4 8.25 375 1.93 11.3 380 1.16 385 0.77 Temperature dependence given by: ln σ = ln σ (298) + B (T -298/K) Quantum Yield 8 = 1.0 over the wavelength range 230–380 nm. www.atmos-chem-phys.net/8/4141/2008/ Atmos. Chem. Phys., 8, 4141–4496, 2008 4496 R. Atkinson et al.: Evaluated kinetic and photochemical data for atmospheric chemistry Comments on Preferred Values There is good agreement between all the reported absorption spectra of CH I . The cross section data of Roehl et al. (1997) and 2 2 Mossinger ¨ et al. (1998) are in excellent agreement both in terms of the absolute absorption cross sections, and its temperature dependence as a function of wavelength, expressed in terms of a single parameter B in the equation ln σ = ln σ (298) + B (T - 298/K). The preferred values for the cross-sections are a simple mean from both data sets, and the temperature dependence of Mossinger ¨ et al. (1998) is adopted since it is based on a wider range of temperature. The study of the photodecomposition of CH I by Schmitt and Comes (1980) indicated dissociation via reaction (1), in line 2 2 with other alkyl iodides, occurring with a quantum yield of unity. Reaction (2) may be important following absorption in the band centered at λ = 215 nm. A signiﬁcant fraction of I atoms are formed in the excited state in the tropospheric photolysis of CH I . 2 2 References Baughcum, S. L. and. Leone, S. R.: J. Chem. Phys. 72, 6531, 1980. Koffend, J. B. and Leone, S. R.: Chem. Phys. Lett. 81, 136, 1981. Mossinger ¨ , J. C., Shallcross, D. E. and Cox, R. A.: J. Chem. Soc. Faraday Trans. 94, 1391, 1998. Roehl, C. M., Burkholder, J. B., Moortgat, G. K., Ravishankara, A. R. and Crutzen, P. J.: J. Geophys. Res. 102, 12819, 1997. Schmitt, G. and Comes, F. J.: J. Photochem. 14, 107, 1980. Atmos. Chem. Phys., 8, 4141–4496, 2008 www.atmos-chem-phys.net/8/4141/2008/

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Evaluated kinetic and photochemical data for atmospheric chemistry: Volume IV – gas phase reactions of organic halogen species

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